Evolution of female colour polymorphism in damselflies: testing the hypotheses

The existence of several female colour morphs is a conspicuous characteristic of many damselflies that show one male-like (androchrome) and several nonmale-like (gynochrome) morphs. We tested several adaptive hypotheses and the null model for the maintenance of female polychromatism (one androchrome and two gynochromes) in the damselfly Ceriagrion tenellum. We tested the null model by comparing the degree of genetic differentiation between the colour locus and a set of 19 neutral RAPD loci in five populations. Our results indicate that selection is acting to maintain similar frequencies between populations at the colour locus. Using mark–recapture techniques we found that mating success is not dependent on female coloration. We tested the mimicry hypothesis by presenting live and dead models to males. Dead models were highly attractive irrespective of coloration. In contrast, with live models males could not distinguish between androchromes and other males, and were more attracted to gynochrome females. Despite this, within populations morph frequencies remained constant over time and mating was at random with respect to female coloration. However, there was a positive relationship between male density and androchrome frequency in a comparative study of eight populations. We discuss our results in the framework of sexual conflict theory and suggest that andro- and gynochrome females are using different strategies to control their number of matings. The different morphs might be maintained in a balanced polymorphism by a combination of density- and frequency-dependent mechanisms.Copyright 2002 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour     

Maintenance of polymorphic females: do parasites play a role?

The role of parasites in explaining maintenance of polymorphism is an unexplored research avenue. In odonates, female-limited color polymorphism (one female morph mimicking the conspecific male and one or more gynochromatic morphs) is widespread. Here we investigated whether parasitism contributes to color polymorphism maintenance by studying six species of female dimorphic damselflies using large databases of field-collected animals. We predicted that androchrome females (male mimics) would be more intensively parasitized than gynochrome females which is, according to previous studies, counterbalanced by the advantages of the former when evading male harassment compared to gynochrome females. Here we show that in Ischnura denticollis and Enallagma novahispaniae, androchrome females suffer from a higher degree of parasitism than gynochromatic females, and contrary to prediction, than males. Thus, our study has detected a correlation between color polymorphism and parasitic burden in odonates. This leads us to hypothesize that natural selection, via parasite pressure, can explain in part how androchrome and gynochrome female color morphs can be maintained. Both morphs may cope with parasites in a different way: given that androchrome females are more heavily parasitized, they may pay a higher fecundity costs, in comparison to gynochrome females.     

Do group dynamics affect colour morph clines during a range shift?

Species exhibiting colour polymorphism are thought to have an ecological advantage at the landscape scale, because spatial segregation of alternatively adapted ecotypes into diverse habitats can increase the species' niche breadth and thus confer greater geographic range size. However, morph frequencies are also influenced by intrapopulational processes such as frequency‐ or density‐dependent social interactions. To identify how social feedback may affect clinal variation in morph frequencies, we investigated reciprocal interactions between morph‐specific thermal tolerance, local climatic conditions and social environments, in the context of a colour‐morph frequency cline associated with a recent range expansion in blue‐tailed damselflies (Ischnura elegans) in Sweden. Cold tolerances of gynochromes (female‐like female morph) were positively correlated with local gynochrome frequencies, suggesting a positive frequency‐dependent fitness benefit. In contrast, androchrome (male‐mimic female morph) cold tolerances were improved following recent exposure to cold weather, suggesting a beneficial environmental acclimation effect. Thus, according to an environment‐matching hypothesis for clinal variation, androchrome frequencies should therefore increase towards the (cooler) range limit. In contrast to this prediction, gynochrome frequencies increased at the expanding range limit, consistent with a positive frequency‐dependent social feedback that is beneficial when invading novel climates. Our results suggest that when phenotypes or fitnesses are affected by interactions with conspecifics, beneficial social effects on environmental tolerances may (i) facilitate range shifts, and (ii) reverse or counteract typical patterns of intraspecific interactions and environment‐matching clines observed in stable populations observed over broader geographic scales.     

Hybridization and the inheritance of female colour polymorphism in two ischnurid damselflies (Odonata: Coenagrionidae)

Female‐limited polychromatism is frequent in many species of Odonata. Ischnura elegans has three colour morphs: one male‐like coloured (androchrome) and two additional gynochrome brown morphs (infuscans and rufescens‐obsoleta morphs). A total of 19 progenies obtained from once‐mated females were reared in the laboratory in three generations. Results indicate that the colour morphs are controlled by the same genetic system as previously described for I. graellsii, i.e. an autosomal locus with female‐limited expression and with three alleles with a hierarchy of dominance (p^a > pⁱ > p°). Five interspecific crossings between female I. graellsii and male I. elegans, five crossings between hybrid females and male I. elegans and one crossing between female I. graellsii and a hybrid male further confirmed that the genetic system is the same in both species. A survey of morph frequencies in north‐west Spain revealed that I. elegans shows high variability in androchrome frequency (4–91%) between nearby populations, whereas in I. graellsii androchromes never are the majority morph (5–40%). The highest androchrome frequency in I. graellsii was found in populations closest to a locality where both species have hybridized, and that now has the highest androchrome frequency of I. elegans. We hypothesize that I. elegans genes have been incorporated into the genome of I. graellsii resulting in increased androchrome frequency in the latter species. Low androchrome frequency in I. elegans seems also related to the influence of I. graellsii genes. Therefore, we suggest that hybridization between both taxa is contributing to the temporal maintenance of contrasting androchrome frequencies in nearby populations. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85 , 471–481.     

Female Colour Polymorphism and Unique Reproductive Behaviour in <Emphasis Type="Italic">Polythore</Emphasis> Damselflies (Zygoptera: Polythoridae)

We studied Polythore damselflies by mark-recapture techniques in the Jatun Sacha Biological Reserve (Ecuador) for a period of 48 days in October–December 2014. Three species were found: Polythore mutata (MacLachlan) was the commonest species (111 individuals marked), Polythore derivata (MacLachlan) was rare (24 individuals) and Polythore concinna (MacLachlan) occasional (four individuals). In P. mutata, we found two phenotypes amongst females, one of them with a white band on the wings, very similar in colouration to the conspecific male (androchrome), and the other with an amber band (gynochrome). The recapture of marked females indicates that both phenotypes are maintained since emergence to maturation and are not age-related (i.e. polymorphism). Androchromes represent 40% of females observed. The colour of the wing band showed an age-dependent change in size with opposite trends between sexes, increasing in males and decreasing in females. Males and females were observed to return to the same forest locations in different days. Courtships and ovipositions involving androchrome females were not observed. No matings were observed in any morph. In contrast, we recorded two consecutive matings of one female P. derivata. We found that Polythore males grasp the mesothorax of females during mating instead of the prothorax as in other Zygoptera. We discuss the rarity of reproductive behaviour in this genus and how female morphs might be maintained.     

Age-specific survival and reproductive performances in fur seals: evidence of senescence and individual quality

Life history theory hypothesises that breeding events induce reproductive costs that may vary among individuals. However, the growing number of studies addressing this question are taxonomically biased, therefore impeding the generalisation of this hypothesis, especially with regard to marine top predators. This study investigated age‐related survival and breeding performances in subantarctic fur seal (Arctocephalus tropicalis) females from Amsterdam Island, southern Indian Ocean. Using multistate capture–recapture models on data obtained from known‐age tagged females over eight consecutive years, we tested for evidence of senescence, individual quality, and reproductive costs in terms of future survival and fecundity. Adult female yearly survival appeared high and constant throughout time. While a two age‐class model was preferred in non‐breeders, breeding females exhibited three age classes with a maximum survival for the prime‐age class (7–12 years). Survival and reproductive probabilities decreased from 13 years onward, suggesting senescence in this population. Survival was lower for non‐breeders than for breeders, among both prime‐aged (0.938 vs 0.982) and older (0.676 vs 0.855) females. Furthermore, non‐breeders exhibited higher probabilities of being non‐breeders the following year than did breeders (0.555 vs 0.414). Such results suggest consistency in female breeding performance over years, supporting the hypothesis that non‐breeding tend to occur among lower quality individuals rather than representing an alternative strategy to enhance residual reproductive value. However, the high proportion of females that did not breed during two consecutive years, and the lower probability of being a successful breeder after a greater reproductive effort confirmed the existence of reproductive costs, especially during the second half of the lactation. These results also suggest that younger age‐classes included a higher proportion of lower quality individuals, which are likely to face higher costs of reproduction. Such hypotheses lead to consider the first breeding event as a filter generating a within‐cohort selection process in females.     

Interspecific crossing between blue‐tailed damselflies Ischnura elegans and I. senegalensis in the laboratory

Ischnura species (Odonata) are among the most common damselflies in the world, which often exhibit female color polymorphisms. One morph, called androchrome, is similar to males in its color pattern, whereas the other morphs, generally referred to as gynochromes, exhibit female‐specific colors. In several Ischnura species, the female polymorphism is heritable, although molecular and genetic mechanisms remain largely unknown. The dominant‐recessive patterns of the female color morphs may differ between species. For example, androchromic females are dominant to gynochromic females in Ischnura elegans, whereas androchromic females are recessive in Ischnura senegalensis. Here we report a case of interspecific hybridization between a gynochrome female of I. elegans and a male of I. senegalensis in the laboratory. We obtained 61 hybrid adult offspring, of which all 31 females were of gynochrome morph. DNA analyses of the hybrids confirmed that nuclear DNA sequences were derived from both parent species, whereas mitochondrial DNA sequences were maternally inherited. In the hybrids, the postocular spots of female heads, the shape of male appendages, and the color of female's cerci resembled those of I. elegans, whereas the size of abdominal blue spots was similar to that of I. senegalensis. The shape of prothorax and basal abdominal markings were intermediate in females. The larval developmental traits and the morphological changes in the final larval instar of the hybrids were similar to those of I. senegalensis. To our knowledge, this is the first report of hybrids between two damselfly species with different dominant‐recessive patterns of female color morphs.     

Experimental manipulation reveals differential effects of colour pattern on survival in male and female pygmy grasshoppers

Populations of pygmy grasshoppers, Tetrix subulata, exhibit genetically coded discontinuous variation in colour pattern. To determine whether the dynamics of this polymorphism is likely to be affected by selective processes, rather than by stochastic events, we experimentally manipulated colour patterns of free-ranging grasshoppers and then calculated and controlled for differences in capture probabilities between categories of individuals before estimating and testing for differences in survival using mark–recapture data and program SURGE . We found that paint treatment had a significant effect on survival, and that the relationship between colour pattern and survival was different in males and females. Our analyses also revealed significant differences between sexes in relative frequencies of natural colour morphs, body size, activity pattern, dispersal distance and microhabitat use. These findings accord with the hypothesis that colour pattern and behaviour jointly determine susceptibility to visual predators. Our data enable us to reject the null-hypothesis that colour pattern is a selectively neutral character and that the polymorphism is maintained solely by stochastic processes, such as random genetic drift and founder events. Indeed, the effect of dorsal coloration on survival, together with associations between colour pattern and many biologically important traits (body size, behaviour, thermal capacity, physiology and reproductive performance), suggests that colour pattern is likely to significantly influence individual fitness, and that the polymorphism must be maintained by some active process, such as spatially variable selection in combination with gene flow. The possible role of colour polymorphism as an intermediate stage in the evolution of sexual dichromatism in animals is discussed.     

Alternative reproductive strategies and the maintenance of female color polymorphism in damselflies

Genetic polymorphisms are powerful model systems to study the maintenance of diversity in nature. In some systems, polymorphisms are limited to female coloration; these are thought to have arisen as a consequence of reducing male mating harassment, commonly resulting in negative frequency‐dependent selection on female color morphs. One example is the damselfly Ischnura elegans, which shows three female color morphs and strong sexual conflict over mating rates. Here, we present research integrating male tactics, and female evolutionary strategies (female mating behavior and morph‐specific female fecundity) in populations with different morph‐specific mating frequencies, to obtain an understanding of mating rates in nature that goes beyond the mere measure of color frequencies. We found that female morph behavior differed significantly among but not within morphs (i.e., female morph behavior was fixed). In contrast, male tactics were strongly affected by the female morph frequency in the population. Laboratory work comparing morph‐specific female fecundity revealed that androchrome females have lower fecundity than both of the gynochrome female morphs in the short term (3‐days), but over a 10‐day period one of the gynochrome female morphs became more fecund than either of the other morphs. In summary, our study found sex‐specific dynamics in response to different morph frequencies and also highlights the importance of studying morph‐specific fecundities across different time frames to gain a better understanding of the role of alternative reproductive strategies in the maintenance of female‐limited color polymorphism.     

Female colour polymorphism covaries with reproductive strategies in the tawny owl Strix aluco

Variation in coloration with a strong underlying genetic basis is frequently found in birds, insects, anurans, molluscs and plants. Although such a variation can be large, little is known about its functional value. Correlative data, however, can help suggest testable hypotheses about potential covariation between reproductive parameters and a colour polymorphism displayed by individuals belonging to a single population. In this context, we studied two Swiss populations of tawny owls Strix aluco , a polymorphic species that varies in coloration from reddish-brown to grey. Observations in the first population showed that although greyer females had shorter tarsi, they produced heavier offspring in two of three years. Pairing with respect to plumage coloration was not significantly disassortative, indicating that these correlations were probably not inflated by plumage coloration of the mate. In the second population, where breeding females had been monitored for 14 years, the proportion of all breeding females that were reddish-brown was greater in years when the breeding density was lower. Capture-recapture analyses show that the latter result is explained by the fact that greyish females bred less often than reddish-brown females, although their survival probability was similar. The number of greyer breeding females was greater when spring/summer temperatures were lower. When combined, the results from the two populations lend support to the hypothesis that grey females do not breed every year, but produce offspring of higher quality. Whatever the mechanism underlying the correlations reported in this study, colour polymorphism in female tawny owls appears to reflect some components of individual quality.     

A demographic analysis of population responses to the manipulation of adult males in <Emphasis Type="Italic">Calomys venustus</Emphasis> (Rodentia,Sigmodontinae)

In many species of mammals, adults play an important role in influencing the survival and/or reproduction of juveniles. Adult males could have a negative effect on population density when their absence becomes a limiting factor in female fertilization. We tested the hypotheses that the absence of overwintering males (adult males) reduces the population growth rate through a delay in the onset of reproductive activity of Cohort 1 females in Calomys venustus populations. The study was carried out in two control and two experimental enclosures (0.25 ha). Adult males were removed after their offspring were born. Weekly trapping sessions were carried out from spring to autumn. To estimate population growth rates (λ), apparent survival (ϕ) and seniority probability (γ) were estimated using capture–mark-recapture models. Models were constructed with these two parameters and recapture probability (p) constrained to vary as a function of time, enclosure and/or treatment. We derived estimates of population growth rates through the estimates of ϕ and γ. The best models for ϕ and γ did not show a treatment effect. Variability between the four enclosures was greater than between control and experimental enclosures. Enclosures had different growth rates at the beginning of the study but were equaled at the end. Temporal variation in population growth rates was a result of temporal variation of γ. The two controls showed the highest growth rates earlier in time. The results did not support the hypothesis tested in this study. It seems that the number of overwintering males do not affect the population growth rate.     

COSTLY INFIDELITY: LOW LIFETIME FITNESS OF EXTRA‐PAIR OFFSPRING IN A PASSERINE BIRD

Extra‐pair copulation (EPC) is widespread in socially monogamous species, but its evolutionary benefits remain controversial. Indirect genetic benefit hypotheses postulate that females engage in EPC to produce higher quality extra‐pair offspring (EPO) than within‐pair offspring (WPO). In contrast, the sexual conflict hypothesis posits that EPC is beneficial to males but not to females. Thus, under the sexual conflict hypothesis, EPO are predicted to be no fitter than WPO. We tested these two hypotheses in a 12‐year dataset with complete life‐history and pedigree information from an isolated island population of house sparrows (Passer domesticus). We compared fitness components of EPO and two types of WPO: (1) WPO from genetically polyandrous “unfaithful” mothers, and (2) WPO from genetically monogamous mothers. We found that all three groups of offspring had similar probabilities of hatching and nestling survival. Unexpectedly, EPO had the lowest probability of recruiting into the breeding population and the lowest lifetime reproductive output. Our results indicate that EPO incurred indirect genetic costs, rather than benefits, which is contrary to indirect benefit models. Importantly, the indirect costs we observed are also underappreciated in current sexual conflict models. Our results call for improved theoretical frameworks that incorporate indirect costs by extending current sexual conflict models.     

Sex identification and PIT‐tagging: tools and prospects for studying intersexual differences in freshwater fishes

This study evaluated a technique to allow the long‐term monitoring of individual fishes of known sex in the wild using sex confirmation in close proximity to the reproductive period combined with individual tagging. Hundreds of partially migratory roach Rutilus rutilus were tagged with passive integrated transponders (PIT) following sex determination in spring and various performance measures were compared with fish tagged outside the reproductive period in autumn. Short‐term survival was >95% for R. rutilus sexed and tagged under natural field conditions. Total length (L_T) did not affect the probability of survival within the size range tagged (119–280 mm), nor were there differences in timing of migration the following season between individuals sexed and tagged in spring and individuals tagged in autumn (i.e. outside the reproductive period). Also, a similar per cent of R. rutilus sexed and tagged in spring and tagged in autumn migrated the following season (34·5 and 34·7%). Moreover, long‐term recapture data revealed no significant differences in body condition between R. rutilus individuals sexed and tagged in spring, individuals tagged in autumn and unmanipulated individuals. The observed sex ratio of recaptured fish did not differ from the expected values of equal recapture rates between males and females. Hence, there is no observable evidence for an adverse effect of tagging close to the reproductive period and therefore this method is suitable for studying intersexual differences and other phenotypic traits temporarily expressed during reproduction at the individual level in fishes.     

Female survival,lifetime reproductive success and mating status in a passerine bird

In facultatively polygynous birds, secondary females of polygynously mated males typically have reduced annual reproductive success, because polygynous males provide less paternal care than monogamous males. Life history theory predicts that, as a result of increased reproductive investment, secondary females should suffer from reduced survival and lifetime reproductive success, but previous studies provided only weak support for this hypothesis. We used 7 years of data to study the fitness of female collared flycatchers Ficedula albicollis in relation to mating status by estimating survival and lifetime reproductive success. Taking differences in recapture probability into account, a mark-recapture analysis revealed that females observed at least once to breed as secondary female had higher survival than other females. This relationship was not confounded by laying date, because when we assessed the impact of laying date on survival, we found similar survival patterns. Females of polygynous males had reduced breeding success in terms of number of young fledged during the current reproductive event. However, during their lifetime females found at least once in primary or secondary mating status produced significantly more eggs, and at least the same number of fledglings and recruits as monogamous females. Thus, in the collared flycatcher, females of polygynously mated males seem to suffer from mating status during the most recent reproductive event, but considering survival and lifetime reproductive success, the apparently disadvantageous mating event is not necessarily associated with reduced residual reproductive value.     

Dorsal pattern polymorphism in female Iberian wall lizards: differences in morphology,dorsal coloration,immune response,and reproductive investment

Sex‐specific colour polymorphisms have been extensively documented in many different taxa. When polymorphism in colour pattern is restricted to females, the condition is known as female‐limited pattern polymorphism (FPP), which has been less commonly addressed in vertebrates. FPP is present in several lizard species, although most research on lizards has focused on carotenoid‐ and pteridine‐based coloration and not on melanin‐based polymorphisms. In the present study, we focus on Iberian wall lizards, Podarcis hispanicus, where two female melanin‐based dorsal patterns can be clearly distinguished: striped and reticulated‐blotched. We indirectly tested the hypothesis that selection acts differentially among P. hispanicus female morphs to create alternative morph‐specific phenotypic optima at different levels by investigating whether morphs differ in fitness proxies. We specifically examined whether the two female dorsal pattern morphs differed in adult morphology, dorsal coloration, immune response, reproductive investment, and growth. We did not find a relationship between melanin‐based coloration and hatchling growth and immune response, despite a correlation between these traits possibly being expected as a result of pleiotropy in the melanocortin system. However, our results show that female dorsal morphs in P. hispanicus differ in terms of adult morphology, dorsal coloration, and reproductive investment. Reticulated‐blotched P. hispanicus females had deeper heads and longer femora, less melanin, and more brownish coloration, and also had larger and heavier hatchlings than striped females.     

Variation in Survival and Harvest Rates in Florida Mottled Duck

The Florida mottled duck (Anas fulvigula fulvigula) inhabits a relatively small range of approximately 90,000 km² within peninsular Florida, USA, and is threatened by habitat loss and genetic introgression with feral mallards (Anas platyrhynchos). Moreover, the Florida mottled duck population status has not been assessed for more than a decade. We used band-recovery and recapture data from 2000–2013 to examine geographic and demographic factors that influence the survival of Florida mottled ducks and to determine whether survival and harvest probabilities have changed over time. Mean survival probabilities were higher for birds banded in the southern portion of their Florida range than for those banded in the northern portion and higher for adult males than for adult females in both areas. Harvest probabilities increased in the northern extent of its range in Florida for adults and juveniles and remained relatively constant in the southern portion of its range during the study period. Mean harvest probabilities for adult males in both areas were higher than for adult females. Mean harvest probability for juvenile females was higher than that for juvenile males in the north but was similar between the sexes in the south. Our results suggest that mortality rates are generally greater in the northern portion of the Florida mottled duck range because of regional differences in habitat distribution and permanence and in how mottled ducks and humans use wetlands in these areas. We suggest increasing conservation efforts in the north portion of the Florida mottled duck range and improving inferences from leg banding by incorporating live recapture data. © 2020 The Wildlife Society.     

Seasonal reproductive costs contribute to reduced survival of female greater sage‐grouse

Tradeoffs among demographic traits are a central component of life history theory. We investigated tradeoffs between reproductive effort and survival in female greater sage‐grouse breeding in the American Great Basin, while also considering reproductive heterogeneity by examining covariance among current and future reproductive success. We analyzed survival and reproductive histories from 328 individual female greater sage‐grouse captured between 2003 and 2011, and examined the effect of reproductive effort on survival and future reproduction. Monthly survival of females was variable within years, and this within‐year variation was associated with distinct biological seasons. Monthly survival was greatest during the winter (November–March; Φ_W= 0.99 ± 0.001 SE), and summer (June–July; Φ_S= 0.98 ± 0.01 SE), and lower during nesting (April–May; Φ_N= 0.93 ± 0.02 SE) and fall (August–October; Φ_F= 0.92 ± 0.02 SE). Successful reproduction was associated with reduced monthly survival during summer and fall, and this effect was greatest during fall. Females that successfully fledged chicks had lower annual survival (0.47 ± 0.05 SE) than females who were not successful (0.64 ± 0.04 SE). Annual survival did not vary across years, consistent with a slow‐paced life history strategy in greater sage‐grouse. In contrast, reproductive success varied widely, and was positively correlated with annual rainfall. We found evidence for heterogeneity among females with respect to reproductive success; compared with unsuccessful females, females that raised a brood successfully in year t were more than twice as likely to be successful in year t+ 1. Female greater sage‐grouse incur costs to survival associated with reproduction, however, variation in quality among females may override costs to subsequent reproductive output.     

Lifetime fitness and age‐related female ornament signalling: evidence for survival and fecundity selection in the pied flycatcher

Ornaments displayed by females have often been denied evolutionary interest due to their frequently reduced expression relative to males, habitually attributed to a genetic correlation between the sexes. We estimated annual and lifetime reproductive success of female pied flycatchers (Ficedula hypoleuca) and applied capture–mark–recapture models to analyse annual survival rates in relation to the patterns of expression (absence/presence) of an ornament displayed by all males and a fraction of females. Overall, the likelihood of expressing the ornament increased nonlinearly with female age and was due to within‐individual variation, not to the selective appearance or disappearance of ornament‐related expression of phenotypes in the population. Accordingly, expressing the forehead patch in a given year did not influence survival probability. However, those females expressing the ornament at early ages (1–2 years old) enjoyed survival advantages throughout lifetime. Although ornamented females had higher lifetime fecundity and fledging success, their yearly reproductive performance, in terms of fledging productivity, decreased as they aged so that, late in life, ornamented females reared fewer offspring than nonexpressing females of the same age. In addition, both strategies (expressing vs. not expressing the trait) returned similar fitness payoffs in terms of recruited offspring. Our results support the hypothesis that fecundity and survival selection are involved in the displaying of this ‘male’ ornament by females.     

Scent of a Dragonfly: Sex Recognition in a Polymorphic Coenagrionid

In polymorphic damselflies discrimination of females from males is complex owing to the presence of androchrome and gynochrome females. To date there is no evidence that damselflies use sensory modalities other than vision (and tactile stimuli) in mate searching and sex recognition. The results of the present behavioural and electrophysiological investigations on Ischnura elegans, a polymorphic damselfly, support our hypothesis that chemical cues could be involved in Odonata sex recognition. The bioassays demonstrate that males in laboratory prefer female to male odour, while no significant difference was present in male behavior between stimuli from males and control. The bioassays suggest also some ability of males to distinguish between the two female morphs using chemical stimuli. The ability of male antennae to perceive odours from females has been confirmed by electrophysiological recordings. These findings are important not only to get insight into the chemical ecology of Odonata, and to shed light into the problem of olfaction in Paleoptera, but could be useful to clarify the controversial aspects of the mating behavior of polymorphic coenagrionids. Behavioural studies in the field are necessary to investigate further these aspects.     

Consequences of breeding system for body condition and survival throughout the annual cycle of tidal marsh sparrows

An individual's body condition and probability of survival can change throughout the annual cycle, based on the combined effects of many factors, including reproductive investment during breeding, colder temperatures during winter, and elevated risks during migration. We evaluated body condition and survival during breeding and non‐breeding periods in two closely related species with notably different reproductive systems. Male and female saltmarsh sparrows Ammodramus caudacutus represent extremes in parental care: males perform none, leaving females to do everything from build nests to care for fledglings. In contrast, male and female seaside sparrows A. maritimus have bi‐parental care and similar levels of reproductive investment, intermediate between male and female saltmarsh sparrows. Our results are consistent with the idea that females experience non‐lethal effects of reproduction, and that differences between the breeding season and winter affect condition. In both species, females had lower scaled mass index (SMI) values than males during both breeding and non‐breeding seasons, and female saltmarsh sparrows had lower SMI values than female seaside sparrows. Females carried more fat than males during the breeding season, and female, but not male, fat and muscle scores decreased over time, which is consistent with the adaptive mass hypothesis. In winter, all groups carried more fat and had higher muscle scores than when breeding, despite having lower SMI scores. Although we observed variation in body condition, within‐season survival was uniformly high in both seasons, suggesting that sex, species, season, body size, and body condition have little impacts on within season survival. Comparisons with previously‐published estimates of annual adult survival suggest that most mortality occurs during migration, even in these short‐distance migrants. The importance of considering multiple aspects of body condition, multiple seasons, and difficult‐to‐monitor events, such as migration, should not be ignored when thinking about the events and processes that cumulatively determine population dynamics.