Gestation temperature affects sexual phenotype, morphology, locomotor performance, and growth of neonatal brown forest skinks, Sphenomorphus indicus

We maintained pregnant Sphenomorphus indicus under four thermal conditions for the whole gestation period to assess the effects of gestation temperature on offspring phenotypes. Parturition occurred between late June and early August, with females at high body temperatures giving birth earlier than those maintained at low body temperatures. Litter size, litter mass, and postpartum body mass did not differ among treatments, and females with relatively higher fecundity produced smaller offspring. Females gave birth to predominantly female offspring (85.7% of the 14 sexed offspring were females) at 24 °C and to predominantly male offspring (76.5% of the 17 sexed offspring were males) at 28 °C. Females with the opportunity to regulate body temperature produced a mix of sexes that did not differ from equality. Offspring produced in different treatments differed in head size, hind-limb length, and tympanum length, but not in snout-vent length, tail length, body mass, fore-limb length, and eye length. Offspring produced at 28 °C were not only smaller in head size, but also shorter in hind-limb length and tympanum length than those offspring produced at lower temperatures. Offspring produced at 28 °C performed more poorly in the racetrack and grew more slowly than offspring produced in the other three treatments. Taken together, our results show that S. indicus might be a temperature-dependent sex determination species and that offspring phenotypes are impaired at high gestation temperatures but maximized at relatively low gestation temperatures.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 453–463.     

Who's your daddy? Paternity testing reveals promiscuity and multiple paternity in the carnivorous marsupial Dasyurus maculatus (Marsupialia: Dasyuridae)

Female promiscuity is common among mammals but its advantages, particularly for marsupials, remain unclear. Using microsatellite DNA from pouch young of known mothers, we identified the most likely fathers of 25 wild spotted-tailed quolls ( Dasyurus maculatus ) from six litters. We aimed to determine whether young within the same litter had different fathers, and whether breeding success of males was associated with large body mass (consistent with inter-male competition) or scrotal width (consistent with sperm competition). We also explored the possible influence of promiscuity on relatedness within litters. Finally, we used data on paternity and relatedness to make inferences regarding movement and dispersal.
Four litters were sired by more than one male, and three males sired offspring in more than one litter. Known fathers had higher body mass, but not scrotal width, than males of unknown paternity status, suggesting that males may compete for access to females. Sires were less related to dams than expected by chance, and litters with multiple paternity had lower relatedness than litters sired by a single male.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 1–7.     

Body size in proboscideans, with notes on elephant metabolism

Mass estimates for a number of fossil proboscideans were computed using regression analyses on appendicular bones to body mass, for seven specimens of modern elephants, for which body masses had been recorded prior to death. The marked differences in physical proportions between extant Loxodonta and Elephas , implying substantial differences in body mass at any given shoulder height, were not present in their long bone parameters. Length and least circumferences proved to be the best parameters for prediction of body mass. Some extinct proboscideans, notably certain Mammuthus and Deinotherium , were much larger than extant elephants. Both the basal and the field metabolic rates of extant elephants are lower than predicted for a hypothetical mammal, in accordance with their body size and subsistence on low-quality foods. The feeding quantities often ascribed to extant wild elephants are exaggerated, and would in fact have sufficed to nourish much larger species.  © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society , 2004, 140 , 523–549.     

Size matters: the (negative) allometry of copulatory duration in mammals

The amount of time taken to copulate varies enormously among mammals. Because copulation likely exposes animals to an increased risk of predation, and uses time and energy that could be spent on foraging, smaller mammals (which are vulnerable to more predators and have a shorter time-to-starvation than larger mammals) should spend less time copulating than do larger mammals. Furthermore, if extended copulation reflects competition among males, then the duration of mating (after correction for body size) should be greater in mammals in which females mate with more than one male. We tested these predictions using comparative data from 113 mammalian species in 85 genera, 40 families, and 14 orders, while controlling for the effect of phylogeny. We found: (1) the relationship between duration of copulation and body size to be negative, not positive; (2) no relationship with inferred multiple mating by females (based upon relative testes mass). We suggest that small mammals may find the sustained maneuvering and body positioning of copulation easier than do large mammals. This hypothesis is supported by an apparently isometric relationship between duration of copulation and ratio of power to mass.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 185–193.     

Acclimation is beneficial at extreme test temperatures in the Danube crested newt, Triturus dobrogicus (Caudata, Salamandridae)

Despite many studies demonstrating the effect of acclimation on behavioural or physiological traits, considerable debate still exists about the evolutionary significance of this phenomenon. One of the unresolved issues is whether acclimation to warmer temperature is beneficial at treatment or at more extreme test temperatures. To answer this question, we assessed the effect of thermal acclimation on preferred body temperatures ( T _ps), maximum swimming and running speed, and critical thermal maximum ( CT _max) in the Danube crested newt ( Triturus dobrogicus ). Adult newts were kept at 15 °C (control) and 25 °C (treatment) for 8 weeks prior to measurements. We measured T _ps in an aquatic thermal gradient over 24 h, maximum speeds in a linear racetrack at six temperatures (5–33 °C), and CT _max in a continuously heated water bath. T _ps were higher in newts kept at 15 °C than in those kept at 25 °C. The maximum swimming speed did not acclimate. The maximum running speed at 30–33 °C was substantially higher in newts kept at 25 °C than in those kept at 15 °C. CT _max increased with the treatment temperature. Hence, we conclude that the acclimation response to warm temperature is beneficial not at treatment but at more extreme temperatures in newts.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 627–636.     

Photoperiodic influence on the body mass of bumblebee, Bombus terrestris and its copulation duration

Abstract:  The body mass of Bombus terrestris individuals is an important trait for their behavioural performance and colony organization. In this study, colonies were reared under four different photoperiodic regimes, viz. 0 : 24, 8 : 16, 16 : 8 and 24 : 0 h light : darkness (L : D) at 28°C and 50% relative humidity. The changes in body mass were observed at the stages of larvae, pupae and on the day of adult eclosion. Both the wet and dry mass of sexuals gradually decreased with increasing day length. The relationship between body mass and copulation duration revealed that copulation duration was negatively correlated with male body mass, but positively with queen body mass. Higher number of matings by males resulted in significantly higher duration of copulation.     

Convergence and parallelism among cicadas of Argentina and the southwestern United States (Hemiptera: Cicadoidea)

Cicadas of the genera Derotettix in Argentina and Okanagodes in the south-western United States resemble each other in colour, live on salt-tolerant plants ( Atriplex spp. etc.), nearly match the colour of their respective host plants and produce songs above the range of avian hearing. The Argentine cicadas are smaller, but have nearly identical thermal limits for activity measured by the minimum temperature for flight (20–24 °C) and a body temperature at heat torpor (48–49 °C). The species shift activity from basking sites to shade at temperatures above 37 °C, although O .  gracilis rises to a significantly higher temperature (40.7 °C) than its congener (38.2 °C) or Derotettix (37.2 °C). The thermal tolerances are the highest reported for cicada species. A third group using halophytes in Argentina ( Babras sonorivox ) has similar temperature tolerances and is cryptically coloured. The genera are convergent with respect to morphology, coloration, body size, behaviour, habitat choice and host plant selection. The similarities of thermal tolerances and their influence on behaviour can be viewed as parallelism because the underlying mechanisms are the same in all species studied.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 281–288.     

Influence of temperature on silver accumulation and depuration in rainbow trout

To assess the influence of water temperature on silver uptake, rainbow trout Oncorhynchus mykiss ( c . 50 g; held at 13° C) were exposed to 0·1 μM AgNO₃ in ion‐poor water for 1 week at 4 and 16° C without previous temperature acclimation. To assess the influence of temperature on elimination of previously accumulated Ag, rainbow trout were exposed to 0·1 μM AgNO₃ in ion‐poor water for 1 week at 12° C, then were randomly divided amongst two Ag‐free water containers, differing only in temperature (3 and 16° C), for 2 months. In the uptake study greater accumulation of Ag was seen in the gills, plasma and especially the livers and bile of 'warm' rainbow trout (16° C) compared to 'cold' rainbow trout (4° C), which can be explained by the higher metabolic rates of the warmer fish. In the depuration study there was no net elimination of Ag from the livers and bile but there was biphasic elimination of Ag from the gills and plasma of 'warm' and 'cold' fish, but with few differences between them. This indicated that temperature‐dependent processes were less important in Ag elimination than in Ag uptake. Toxicokinetic modelling of Ag uptake by livers indicated four‐fold greater uptake of Ag by 'warm' rainbow trout compared to 'cold' rainbow trout (one compartment uptake model). Elimination of previously accumulated Ag from the plasma was best fitted by a two compartment rate‐constant based model, with approximately half the plasma Ag load eliminated within 24 h, followed by slower elimination of Ag over 2 months.     

Geographic variation in jungle cat (Felis chaus Schreber, 1777) (Mammalia,Carnivora, Felidae) body size: is competition responsible?

There is a striking difference in body size of jungle cats ( Felis chaus ) in the west and the east of their distribution, with Israeli cats being 43% heavier than Indian cats. We tested the hypothesis that increasing competition from other small felids towards the east is responsible for the difference in body size. We measured jungle cat skulls for eight cranial and dental variables and related these to independent variables such as species richness (local and regional), latitude, longitude, temperature, and precipitation. Data from a narrow band between latitudes 24.0°N and 33.9°N, where Bergmann's rule was largely not observed, showed that the western population (≤ 50.0°E longitude) of jungle cats is larger than the eastern (> 60.0°E longitude) population with the size difference being most evident in the upper carnassials (P⁴L). Species richness at the regional level showed a significant negative relation to P⁴L. An even spacing in condylobasal length for a small-cat guild from India through null model analysis indicated the occurrence of character displacement. The results support the hypothesis that competition is responsible for geographical variation in jungle cat body size in the region where Bergmann's rule does not apply. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 163–172.     

Genetic and environmental components of phenotypic variation in body shape among populations of Atlantic cod (Gadus morhua L.)

A common-garden experiment was conducted on larvae to test for genetic differences in body shape among populations of Atlantic cod ( Gadus morhua ). Offspring from four north-west Atlantic regions were reared from hatching to postmetamorphosis at two temperatures (7 ± 1 °C and 11 ± 1 °C) and two food levels (1500 and 4500 prey L⁻¹). Body shape differed between populations and treatments. Population differences were greatest between south-west Scotian Shelf cod and those further north; the former were characterized by a deeper body, larger head, and longer caudal peduncle than cod from the other populations. Significant differences were also observed between two putative populations on the south-west Scotian Shelf, suggesting genetic divergence between spawning aggregations at small spatial scales (< 100 km). Temperature and food supply also influenced body shape, with the effect of the former being more pronounced. Individuals reared at the higher temperature or food level had a deeper body and a larger head than those reared at the lower temperature or food supply. Phenotypic responses to changes in the rearing environment also differed among populations, indicating genetic differences in phenotypic plasticity. Differences between populations in morphology and in phenotypic plasticity suggest genetic divergence at both large (> 1000 km) and small (< 100 km) spatial scales. The genetic differences at large spatial scales counteracted the expected effects of temperature differences in the wild, suggesting countergradient variation in morphology among these populations.  © 2006 Her Majesty the Queen in Right of Canada. Journal compilation © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 88 , 351–365.     

Phenotype and gene flow in a marsupial (Antechinus flavipes) in contrasting habitats

Ecological factors are important drivers of phenotypic divergence, which may lead to incipient speciation. A variety of habitats should be preserved to maintain evolutionary potential. We used the marsupial, the yellow-footed antechinus ( Antechinus flavipes ) as a model species for investigating phenotypic differentiation between animals inhabiting two habitat types in south-eastern Australia: flood-plain river red gum and box–ironbark forests. All tested phenotypic characteristics varied between years at the same sites and therefore were not useful for investigating morphological specialization that may lead to speciation. Males generally were significantly heavier when antechinus densities were lower, but exceptions were found, possibly related to food availability. Teat-number variation recently has been shown to be associated with habitat specialization and incipient speciation within Antechinus agilis . We investigated genetic differentiation associated with this trait in A. flavipes . Population genetic analyses of microsatellite genotypes and mitochondrial DNA haplotypes revealed that sympatric 12-, 13- and 14-teat females in Chiltern forest were part of one freely interbreeding population. Our parentage analyses found two cases where 13-teat mothers produced 12-teat daughters. This suggests either plasticity or paternal genetic influence on the offspring's teat-number phenotype. Laboratory matings may be required to resolve the extent to which teat number is heritable in A. flavipes .  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 94 , 303–314.     

Body mass and habitat correlates of song structure in a primitive group of birds

We assessed relationships between acoustic frequency, body mass, and habitat in tinamous. This monophyletic group of primitive birds comprises c. 47 ground dwelling species whose habitats range from dense humid forest to open grasslands. The relationship between frequency and body mass was found to be negative, while the songs of open-habitat species exhibited higher frequencies and a wider bandwidth than the closed-habitat ones. Residual variation in song frequency, after controlling for the effect of body mass and phylogeny, tends to differ among habitats. However, a statistical test of this pattern was not possible because of the existence of only five pairs of sister species differing in habitat. In spite of this, positive contrasts of bandwidth were associated with positive contrasts of habitat, confirming that songs of open-habitat species have a wider bandwidth than those of their more closed habitat relatives.  © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 77 , 423–430.     

Changes in sperm stores, ejaculate size, fertilization success, and sexual motivation over repeated matings in the common toad, Bufo bufo (Anura: Bufonidae)

Fertilization is of central importance in the determination of reproductive success for both males and females. In species where males have the chance to mate repeatedly within a short period of time, sperm stocks may become depleted and males may have to carefully economize on their sperm reserves. Also, intensive intrasexual competition for females and repeated matings may lead to exhaustion on the behavioural level. To determine whether the reproductive potential of males is limited and if such a limitation is due to behavioural exhaustion or sperm depletion, we experimentally investigated changes in sperm stores, sperm expenditure, fertilization success, and sexual motivation over three repeated matings in the common toad, Bufo bufo , where the breeding season is short and sequential polygyny occurs. At the end of the breeding season, the number of sperm stored in the testes of males mated repeatedly was close to 50% lower than in testes of unmated males. Ejaculate size, which was estimated by applying a novel method allowing direct quantification, decreased by 88% from first to third matings. We also observed a drop in fertilization success from the first two to third matings by 65%, which was largest in males that had started the reproductive season in bad body condition. Some of these males also showed a decreased interest in females in the third mating round. Our results suggest that sperm depletion and loss of sexual motivation may together set a limit to the reproductive potential of common toad males. The present study draws attention to a limitation in reproductive potential, which may occur more often than currently anticipated and has the potential to strongly influence several aspects of reproductive behaviour.  © 2009 The Linnean Society of London, Biological Journal of the Linnean Society , 2009, 96 , 361–371.     

The selective basis for increased egg retention: early incubation temperature determines hatchling phenotype in wall lizards (Podarcis muralis)

The thermal environment during development influences many aspects of the phenotype of hatchling reptiles. We hypothesized that temperature should differentially affect early incubation stages, in which differentiation dominates over growth, and late incubation stages, characterized by high growth rates. To test this idea, we incubated eggs of wall lizard ( Podarcis muralis ) under three regimes with the same mean temperature (29 °C), one constant and two variable with opposite sequences: first cold (25 °C) and then hot (32 °C), and vice versa. Hatchlings incubated at high temperature during the initial period had shorter hindlimbs and tails than those incubated under the other two temperature regimes and shorter heads than those incubated initially at low temperature. Thus, temperature experienced by embryos during the early external incubation period produced similar phenotypic responses compared to those reported in previous studies for the same constant temperature applied over the whole incubation period. Because female wall lizards select lower body temperatures during pregnancy, an increase of intrauterine retention would extend the time of exposure of developing embryos to suitable temperatures. Diminution of body temperature during pregnancy is contrary to the expected pattern under the hypothesis that egg retention has evolved to accelerate development, as proposed by the cold-climate model for evolution of viviparity in squamates, and the results of the present study support the alternative hypothesis of developmental optimization as a special case of the broader maternal manipulation view.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 441–447.     

Taxonomic relationships between Pachycerus and Rhabdorrhynchus (Coleoptera: Curculionidae: Lixinae), with descriptions of two new species of Rhabdorrhynchus from the Arabian Peninsula

Taxonomic relationships between Rhabdorrhynchus and Pachycerus are discussed, and two new species of Rhabdorrhynchus are described: Rhabdorrhynchus sauditus (type locality: Saudi Arabia, As Shāqqah al Yamānīyah, 19°42'N, 40°48'E) and Rhabdorrhynchus emir (type locality: United Arab Emirates, Jebel Ali, 24°59'N, 55°43'E). Some hypotheses on the distribution of the new species in the Arabian Peninsula, based on a biogeographical analysis, are proposed.  © 2008 The Linnean Society of London, Zoological Journal of the Linnean Society , 2008, 152 , 25–37.     

Metamorphic duration: an under-studied variable in frog life histories

Over a narrow temperature range (25.5–28 °C), metamorphic duration in 14 taxonomically diverse frog species ranged from 2.0 to 7.3 days. For 12 species, duration was significantly related to tadpole body-size parameters, especially tail length. For the remainder, duration was longer than expected. Two patterns of tail regression were seen with either rapid or slow regression at the start. Most species lost about 30% of body wet weight during metamorphosis, but two were exceptional: X. laevis lost 58% and F. fitzgeraldi 13%. The results are discussed in the context of Wassersug & Sperry's (1977 ) hypothesis that selection acts to minimize metamorphic duration because metamorphosis is a highly vulnerable stage. Several other factors are outlined as possible determinants of metamorphic duration: developmental constraints, functional trade-offs, phylogeny, predator abundance, adaptive de-coupling, body condition and metabolic and water costs. There is evidence from the data for the operation of several of these factors, especially in species utilizing specialized habitats, and a plea is made for further study of metamorphic duration as an ecologically and evolutionarily important variable in amphibian life histories. Finally, the effects of different temperatures on metamorphic duration are presented for several species, and discussed in terms of local adaptation and reaction norms.  © 2004 The Linnean Society of London, Biological Journal of the Linnean Society , 2004, 83 , 261–272.     

Survival of dried eukaryotes (anhydrobiotes) after exposure to very high temperatures

Organisms that tolerate essentially complete dehydration are said to be in anhydrobiosis, and can be referred to as anhydrobiotes. Those organisms are of great ecological and medical importance, but also provide models for the study of a variety of biological phenomena. We examined the tolerance of selected eukaryotic anhydrobiotes to high temperatures using slow (∼4 °C min⁻¹) and rapid (∼100 °C min⁻¹) heating to 110, 120, 130, and 140 °C. Test organisms were then either returned to storage temperatures close to 22 °C (preheating), or held at those high temperatures for an additional 10 min. Some anhydrobiotes survived slow heating to 130 °C, whereas rapid heating led to a dramatic reduction in survival. None of these organisms encounter anywhere near these high temperatures in nature, so tolerance is not an obvious result of adaptation to current or recent conditions. We speculate that tolerance could have been achieved during the much earlier evolution of these organisms, and has been retained up to the present.  © 2008 The Linnean Society of London, Biological Journal of the Linnean Society , 2008, 93 , 15–22.     

Seed dormancy and germination behaviour in two Euphrasia species (Orobanchaceae) occurring in the Swiss Alps

The optimal time for germination of a seed depends on environmental conditions of its habitat, the life cycle of the germinating plant, and the conditions for successful establishment, growing and reproduction. We studied the germination behaviour of the alpine annual Euphrasia minima and an alpine ecotype of E. salisburgensis in a lowland garden experiment. Seeds of both species and their hybrids germinated at constant (5 °C) and at varying temperatures (3–10 °C), and never before spring after seed ripening. Germination was spread over 3 years, which suggests that the seeds formed a persistent seed bank. The two species together with E. minima and E. minima hybrids differed significantly in the germination rate in the first and second spring.  © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society , 2008, 156 , 649–656.     

Late stage deferral of parturition in the viviparous lizard Niveoscincus ocellatus (Gray 1845): implications for offspring quality and survival

The ability of viviparous lizards to defer parturition after completion of embryonic development is a potentially key strategy for enhancing offspring fitness. Using the spotted snow skink, Niveoscincus ocellatus , we investigated the ability of females to defer birth if placed into cold conditions at the same time, for 1, 2 or 3 weeks at the end of gestation. The ability to defer birth was compared between two populations at each end of the species' altitudinal range. We hypothesized that females from the high elevation population would be less likely to defer parturition under extended periods of poor conditions, thus ensuring that young were not born too late in the season. In all but the 3-week treatment group from the high elevation population, females were able to defer birth when placed under cold conditions: for all groups, there was no treatment effect on offspring phenotype at birth, dispersal distance or survivorship after release. However, there was a significant negative effect of treatment on offspring growth measured after release, with the results differing between the populations. Females from the high elevation population were less able to defer birth under long periods (3 weeks) of cold conditions, and this was accompanied by a decrease in viability of the offspring.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 735–746.