Size Dependent Male Reproductive Tactic in the Two-Spotted Goby (Gobiusculus flavescens)

Male investment in testes and sperm duct gland in the polygamous nest breeding two-spotted goby Gobiusculus flavescens (Fabricius) was investigated in relation to time in reproductive season and individual physical parameters. This small teleost fish is most likely the most abundant species found along the rocky shores of the North East Atlantic. The two-spotted goby has a single reproductive season, during which nest-caring males can raise several clutches of offspring. According to the literature the males are on average larger than the females. Here we report for the first time a population showing a reversal of this trend, with males on average being smaller than females, a difference likely caused by a large proportion of small males. Early in the breeding season these small males have typical sneaker characters, with relatively large testes and small seminal duct glands compared to the larger dominant territorial males. The presence of these two alternative male reproductive tactics is confirmed by histological studies, which shows the presence of sperm in the sperm duct glands (SDG) of smaller males, but not in the SDG of intermediate and larger males. To our knowledge, males with typical sneaker characters have not been reported in earlier studied populations of two-spotted goby. Interestingly we found that testes investment declined significantly over the course of the breeding season, and that this reduction was significantly more pronounced in small compared to the large males. Further, a significant increase in seminal duct gland (SDG) mass was observed for the smaller males over the breeding season. We propose that this indicates a possible shift in mating tactic by smaller males from a parasitic to a nest-holding tactic over the course of the breeding season. Thus, the observed size dependent plasticity in investment in SDG over time suggests that the reproductive tactic of G. flavescens is conditional, and possibly influenced by mate availability and male—male competition.     

Parasitic spawning in sand gobies: an experimental assessment of nest-opening size, sneaker male cues, paternity, and filial cannibalism

Sneaking is common in nest-building fish with paternal care,but the role of nest-opening size in protecting against entryby sneaker males has never been tested before. Using the sandgoby (Pomatoschistus minutus), a fish with exclusive paternalcare, experimental manipulations of nest openings provided nosupport for the hypothesis that nest openings serve as physicalor visual defense or that sneaker males prefer to parasitizenests with wide openings. Female mating preference was alsonot influenced by nest-opening size. However, female courtshipbehavior and visibility were important cues for sneaker males.Most sneak entries occurred when the nest holder was occupiedwith courtship, chasing another sneaker male or nest building.In half the cases of observed sneak entry, the sneaker malefertilized eggs, also when sneaking only occurred before spawning.Sneak entry and its duration were good estimates of stolen paternity,but neither sneak entries nor degree of fertilizations werecorrelated with filial cannibalistic behavior. Testes size didnot explain parasitic spawning success in replicates with geneticallydetermined sneaking. However, all sneaker males without breedingcoloration had huge testes and small sperm duct glands, whereasnest-holding males had small testes and large sperm duct glands,and sneaker males with breeding coloration were intermediate.     

Within‐season variation in sexual selection in a fish with dynamic sex roles

The strength of sexual selection may vary between species, among populations and within populations over time. While there is growing evidence that sexual selection may vary between years, less is known about variation in sexual selection within a season. Here, we investigate within‐season variation in sexual selection in male two‐spotted gobies (Gobiusculus flavescens). This marine fish experiences a seasonal change in the operational sex ratio from male‐ to female‐biased, resulting in a dramatic decrease in male mating competition over the breeding season. We therefore expected stronger sexual selection on males early in the season. We sampled nests and nest‐holding males early and late in the breeding season and used microsatellite markers to determine male mating and reproductive success. We first analysed sexual selection associated with the acquisition of nests by comparing nest‐holding males to population samples. Among nest‐holders, we calculated the potential strength of sexual selection and selection on phenotypic traits. We found remarkable within‐season variation in sexual selection. Selection on male body size related to nest acquisition changed from positive to negative over the season. The opportunity for sexual selection among nest‐holders was significantly greater early in the season rather than late in the season, partly due to more unmated males. Overall, our study documents a within‐season change in sexual selection that corresponds with a predictable change in the operational sex ratio. We suggest that many species may experience within‐season changes in sexual selection and that such dynamics are important for understanding how sexual selection operates in the wild.     

Sperm allocation in the three-spined stickleback

Male three-spined stickleback Gasterosteus aculeatus have a fixed amount of sperm during the breeding season because spermatogenesis is inhibited at this time. A method was developed to estimate ejaculate size in situ by removing the sperm from the male's nest. The reliability of the method was tested using known numbers of sperm. In their first mating, males ejaculated 11·64 × 10⁶ sperm (median), representing c. 5% of the male's sperm store (median 27·88 × 10⁷ sperm). The amount of sperm in the testes was significantly reduced in males that had mated several times (median 8·09 × 10⁷). Additionally, ejaculate size was smaller in these experienced males (median 8·79 × 10⁵). Heavier and larger fish invested absolutely and relatively more sperm in a mating than did lighter and smaller fish. Ejaculate size did not correlate with the mass of the egg clutch.     

Tactic changes in dusky frillgoby Bathygobius fuscus sneaker males: effects of body size and nest availability

Field and laboratory studies were conducted to examine the effects of nest availability and body size on changes in male mating tactics from sneaking to nest‐holding in the dusky frillgoby Bathygobius fuscus. In the field, the body size of nest‐holding males decreased from early to mid‐breeding season, suggesting the possibility of a change in the tactics of sneaker males to nest‐holding. Many sneaker males did not use vacant spawning nests even when size‐matched nests were available, but they continued to reproduce as sneakers. Similarly, in aquarium experiments with available vacant nests, some sneaker males became nest‐holders irrespective of their body size, but some did not. These results showed that nest availability is not a limiting factor for changes in tactics by sneaker males in this species. Because tactic‐unchanged sneaker males were co‐housed with larger nest‐holding males in the tanks, the body size of nearby nest‐holding males may have affected the decision to change tactics for sneaker males. Moreover, smaller individuals among tactic‐changed males tended to spend more time until spawning, probably because they had relatively larger costs and smaller benefits of reproduction as nest‐holding males compared to larger males.     

Alternative reproductive tactics are associated with sperm performance in invasive round goby from two different salinity environments

During male–male competition, evolution can favor alternative reproductive tactics. This often results in a dominant morph that holds a resource, such as a nest for egg laying, which competes with a smaller sneaker morph that reproduces by stealing fertilizations. The salinity environment can influence male growth rates, for example, via osmoregulatory costs, which in turn may influence the use of sneaker tactics for small males competing for mating opportunities. Salinity can also affect sperm directly; however, little is known of how salinity influences sneaker tactics through sperm performance. We sampled males of the invasive round goby (Neogobius melanostomus) from two environments, a freshwater river and a brackish estuary. This fish has two male morphs: nest‐holding dark males and non‐nest‐holding light males. We examined the role of water salinity of 0, 8, and 16 on sperm performance and found that for estuarine males, a salinity of 0 reduced sperm velocity compared to a salinity of 8 and 16. Riverine males had low velocity in all salinities. Sperm viability also decreased by over 30% in 0 salinity, compared to 8 and 16, for fish from both environments. Gobies produce ejaculate contents in specialized glands that could in theory shield sperm in an adverse environment. However, gland contents did not improve sperm performance in our tests. Body mass and age estimates indicate that riverine males invested more in somatic growth compared to estuarine males. Estuarine light morph males had a high enough gonadosomatic index to indicate sneaker tactics. We propose that when sperm performance is low, such as for the riverine males, sneaker tactics are ineffective and will be selected against or phenotypically suppressed. Instead, we interpret the increased investment in somatic growth found in riverine males as a life‐history decision that is advantageous when defending a nest in the next reproductive season.     

Body Size Correlates with Fertilization Success but not Gonad Size in Grass Goby Territorial Males

In fish species with alternative male mating tactics, sperm competition typically occurs when small males that are unsuccessful in direct contests steal fertilization opportunities from large dominant males. In the grass goby Zosterisessor ophiocephalus, large territorial males defend and court females from nest sites, while small sneaker males obtain matings by sneaking into nests. Parentage assignment of 688 eggs from 8 different nests sampled in the 2003–2004 breeding season revealed a high level of sperm competition. Fertilization success of territorial males was very high but in all nests sneakers also contributed to the progeny. In territorial males, fertilization success correlated positively with male body size. Gonadal investment was explored in a sample of 126 grass gobies collected during the period 1995–1996 in the same area (61 territorial males and 65 sneakers). Correlation between body weight and testis weight was positive and significant for sneaker males, while correlation was virtually equal to zero in territorial males. That body size in territorial males is correlated with fertilization success but not gonad size suggests that males allocate much more energy into growth and relatively little into sperm production once the needed size to become territorial is attained. The increased paternity of larger territorial males might be due to a more effective defense of the nest in comparison with smaller territorial males.     

The annual reproductive cycle of the Smooth newt (Triturus vulgaris) in England

Newts were collected throughout the year from both breeding ponds and terrestrial sites and were weighed, measured and dissected; in males, the testes were examined histologically. Smooth newts show post-nuptial gametogenesis such that, during late summer and autumn they are producing mature gametes for the following year's breeding season. In males, the testes are at their smallest size during the spring, when they consist mostly of immature sperm cysts and evacuated tissue, mature sperm having been evacuated into the vasa deferentia during the newts' migration to water. Evacuated testicular tissue is glandular in function and there is evidence that secretions from this tissue control the development of secondary sexual characters: the dorsal crest, fringes of skin on the toes and the dorsal cloacal gland. In both sexes, fat body and liver weights are lowest in the spring and increase in the autumn. In females, oocytes vary in size, depending on the amount of yolk they contain. Only the larger oocytes are laid in a current breeding season, the smaller ones being retained and yolked in late summer and autumn. In both sexes, measures of fecundity (testis size in males, oocyte number in females) are strongly correlated with body size. The finding that male newts have a finite supply of sperm during the breeding season leads to an interpretation of various aspects of male courtship behaviour. These are adaptations for conserving sperm and allocating it to courtship encounters in a way likely to promote male reproductive success.     

Functional infertility among territorial males in two passerine species, the willow warbler Phylloscopus trochilus and the bluethroat Luscinia svecica

Information about male infertility in free-living birds is scarce, but anecdotal and circumstantial evidence suggests that it does occur regularly at a low frequency. In this paper we document three cases of azoospermia in two passerine species, the willow warbler Phylloscopus trochilus and the bluethroat Luscinia svecica at their breeding grounds in South Norway. In willow warblers, two males out of a sample of 50 territory holders had no sperm in their seminal glomera, the storage site of sperm ready for ejaculation. The two males also had very small testes. One out of 48 bluethroat males also had no sperm in the seminal glomera. This male had an extreme asymmetry of the testes, with the right testis being about twice as large as the left. He also failed to fertilize any eggs in his own nest, as well as in neighbouring nests, as revealed by microsatellite genotyping. Thus, the proportion of males without sperm seems to be at a magnitude of a few (2–4) percent in both species. These are among the first estimates of the frequency of azoospermia in wild birds. Our results indicate a significant risk for sexually monogamous females of laying unfertilized eggs, which could favour the evolution of extra-pair copulation as a fertility insurance strategy in females.     

Evolutionary change in testes tissue composition among experimental populations of house mice

Theory assumes that postcopulatory sexual selection favors increased investment in testes size because greater numbers of sperm within the ejaculate increase the chance of success in sperm competition, and larger testes are able to produce more sperm. However, changes in the organization of the testes tissue may also affect sperm production rates. Indeed, recent comparative analyses suggest that sperm competition selects for greater proportions of sperm‐producing tissue within the testes. Here, we explicitly test this hypothesis using the powerful technique of experimental evolution. We allowed house mice (Mus domesticus) to evolve via monogamy or polygamy in six replicate populations across 24 generations. We then used histology and image analysis to quantify the proportion of sperm‐producing tissue (seminiferous tubules) within the testes of males. Our results show that males that had evolved with sperm competition had testes with a higher proportion of seminiferous tubules compared with males that had evolved under monogamy. Previously, it had been shown that males from the polygamous populations produced greater numbers of sperm in the absence of changes in testes size. We thus provide evidence that sperm competition selects for an increase in the density of sperm‐producing tissue, and consequently increased testicular efficiency.     

Testis size depends on social status and the presence of male helpers in the cooperatively breeding cichlid Julidochromis ornatus

Cooperatively breeding animals, in which helpers may participatein reproduction with dominant breeders, are ideal species forexamining intraspecific variation in testis size because theyoften exhibit both monogamous breeding (low risk of sperm competition)and polyandrous breeding (high risk) within a population. However,little is known about testis investment as a result of spermcompetition in these animals. The substrate-brooding cichlidfish Julidochromis ornatus has a cooperatively breeding system,in which some males mate monogamously and other males reproduceas dominant breeders or helpers within cooperatively breedinggroups, in which male helpers frequently sire young. We examinedthe relationship between testis investment and male social statusin relation to the risk of sperm competition. As predicted fromsperm competition models, in groups with male helpers, boththe male breeders and the male helpers invested more in testesmass, compared to breeding males without male helpers. We alsofound a positive relationship between the testes mass of malebreeders and their male helpers, suggesting that males increasetheir investment in reproductive capability under the risk ofsperm competition. Sperm competition models also predict thatlarger testes are associated with increased siring success.Our paternity analysis supported this prediction; we found apositive relationship between testis investment by male helpersand the number of offspring they sired.     

Protracted reproductive seasonality in the male giant panda (Ailuropoda melanoleuca) reflected by patterns in androgen profiles, ejaculate characteristics, and selected behaviors

The female giant panda (Ailuropoda melanoleuca) experiences a brief (24-72 h) seasonal estrus, occurring once annually in spring (February-May). Our aim was to determine the existence and temporal profile of reproductive seasonality in the male of this species. The study was facilitated by 3 yr of access to eight giant panda males living in a large breeding center in China. Seasonal periods for the male were defined on the basis of female reproductive activity as prebreeding, breeding (early, peak, late), and nonbreeding seasons. Testes size, fecal androgen excretion, ejaculated sperm density, and frequency of reproductive behaviors (i.e., locomotion, scent marking, vocalizations) increased (P < 0.05) from the prebreeding period (October 1-January 31) to the early breeding season (February 1-March 21). Testes volume and sperm concentration were maximal from March 22 through April 15, a period coinciding with maximal female breeding activity. The occurrence of male reproductive behaviors and fecal androgen concentrations began declining during peak breeding and continued from April 16 through May 31 (late breeding period), returning to nadir throughout the nonbreeding interval (June 1-September 30). Reproductive quiescence throughout the latter period was associated with basal testes size/volume and aspermic ejaculates. Our results reveal that testes morphometry, fecal androgen excretion, seminal quality, and certain behaviors integrated together clearly demonstrate reproductive seasonality in the male giant panda. The coordinated increases in testes size, androgen production, sperm density, and sexual behaviors occur over a protracted interval, likely to prepare for and then accommodate a brief, unpredictable female estrus.     

Reproductive ecology of the jacky dragon (Amphibolurus muricatus): an agamid lizard with temperature‐dependent sex determination

Abstract The jacky dragon, Amphibolurus muricatus (White, ex Shaw 1790) is a medium sized agamid lizard from the southeast of Australia. Laboratory incubation trials show that this species possesses temperature‐dependent sex determination. Both high and low incubation temperatures produced all female offspring, while varying proportions of males hatched at intermediate temperatures. Females may lay several clutches containing from three to nine eggs during the spring and summer. We report the first field nest temperature recordings for a squamate reptile with temperature‐dependent sex determination. Hatchling sex is determined by nest temperatures that are due to the combination of daily and seasonal weather conditions, together with maternal nest site selection. Over the prolonged egg‐laying season, mean nest temperatures steadily increase. This suggests that hatchling sex is best predicted by the date of egg laying, and that sex ratios from field nests will vary over the course of the breeding season. Lizards hatching from eggs laid in the spring (October) experience a longer growing season and should reach a larger body size by the beginning of their first reproductive season, compared to lizards from eggs laid in late summer (February). Adult male A. muricatus attain a greater maximum body size and have relatively larger heads than females, possibly as a consequence of sexual selection due to male‐male competition for territories and mates. If reproductive success in males increases with larger body size, then early hatching males may obtain a greater fitness benefit as adults, compared to males that hatch in late summer. We hypothesize that early season nests should produce male‐biased sex ratios, and that this provides an adaptive explanation for temperature‐dependent sex determination in A. muricatus.     

Male reproductive suppression in the cooperatively breeding fish Neolamprologus pulcher

In most cooperative breeders, dominants suppress the reproductionof subordinates. However, two previous studies of Neolamprologuspulcher, a cooperatively breeding cichlid fish, have suggestedthat socially subordinate helper males sneak fertilizationsfrom dominant breeding males. If such sneaking does occur, boththeoretical work and empirical studies of other fish speciessuggest that sperm competition will select for increased reproductiveinvestment by sneaker males, relative to more dominant males.To address these issues, we quantified gonadal investment andsperm characteristics of 41 N. pulcher male breeders and 62male helpers from 55 groups in Lake Tanganyika. Gonadal investmentfollowed patterns consistent with reproductive suppression,with breeders having considerably larger testes masses thanhelpers. Breeders also had faster and longer swimming spermand a higher percentage of motile sperm compared to helpers.However, sperm characteristics of large helpers were similarto those of breeders, but these same helpers had lower testesmasses. Thus, large helpers had sperm that were physiologicallyequivalent to that of breeders, but their relatively small gonadsimply that they were reproductively suppressed.     

Timing of breeding and offspring number covary with plumage colour among Gyrfalcons Falco rusticolus

Plumage colour variation exists among Gyrfalcons throughout their Arctic and sub‐Arctic circumpolar distribution, ranging from white through silver and grey to almost black. Although different colour variants coexist within many populations, a few geographical regions, such as northern Greenland, possess a single variant, suggesting that local environments may influence plumage colour variation. In central‐west Greenland (66.5–67.5°N), where multiple colour variants exist, white male Gyrfalcons fathered significantly earlier clutches than grey males. No significant association was observed between female colour and lay date. However, significantly more offspring were produced by both male and female white Gyrfalcons than by grey variants when controlling for lay date, and silver Gyrfalcons produced an intermediate number of offspring for both sexes. This pattern was further supported by breeding plumage colour pairings. Grey females paired with grey males nested significantly later in the season and produced fewer offspring than those paired with white males, whereas no difference in lay date or offspring number was found between white males paired with white or with grey females. The difference in the number of offspring produced at each nest‐site was also inversely correlated with the distance to the nearest neighbouring nest, and grey males nested in closer proximity to other nests compared with white and silver colour variants. These results suggest that factors associated with territory occupancy and timing of breeding may regulate reproductive success differently between colour variants, with directional selection favouring light‐coloured Gyrfalcons and resulting in earlier lay date and a high frequency of white plumage colour variants in this population. Although gene flow exists between our study population and those further north (>75°N), white Gyrfalcons prevail where the breeding season duration is even shorter, suggesting that nesting chronology in combination with genetic drift may play an important role in influencing plumage colour polymorphism among Gyrfalcon populations.     

Variations of sperm release in three batches of zebrafish

By collecting and counting the number of sperm released during separate matings in three batches of zebrafish Danio rerio , aged 3–4, 4–5 and 5–6 months, males were observed to release sperm before the female started laying their eggs. After the female left the nest, the number and motility of sperm and life span of sperm of younger fish were higher than those of older fish in water samples collected under the nest and at the surface of the tank. Sperm were released in the form of sperm trails laid on the nest surface, subsequently active spermatozoa left the trails and moved in the water for several minutes. Sperm trails consisted of bands of viscous material in which the sperm were embedded. In most cases eggs were not laid directly over the sperm trail, suggesting that sperm may contact the eggs after the latter are released into the water. In all the three tested groups there was no significant difference ( P  > 0·05) between the number of sperm collected on some portions of the acetate sheets which lined the nest ceiling. This result demonstrated that the greater activity of younger fish accelerated the sperm dispersal in water. Male sperm duct glands, seminal vesicles, known to secrete mucosubstances are probably involved in the production of sperm trails. The possible influence of insemination on the mating style of zebrafish is discussed.     

Male age and strain affect ejaculate quality in the Mexican fruit fly

Aging in all organisms is inevitable. Male age can have profound effects on mating success and female reproduction, yet relatively little is known on the effects of male age on different components of the ejaculate. Furthermore, in mass‐reared insects used for the Sterile Insect Technique, there are often behavioral differences between mass‐reared and wild males, while differences in the ejaculate have been less studied. The ejaculate in insects is composed mainly of sperm and accessory gland proteins. Here, we studied how male age and strain affected (i) protein quantity of testes and accessory glands, (ii) the biological activity of accessory gland products injected into females, (iii) sperm viability, and (iv) sperm quantity stored by females in wild and mass‐reared Anastrepha ludens (Diptera: Tephritidae). We found lower protein content in testes of old wild males and lower sperm viability in females mated with old wild males. Females stored more sperm when mated to young wild males than with young mass‐reared males. Accessory gland injections of old or young males did not inhibit female remating. Knowledge of how male age affects different ejaculate components will aid our understanding on investment of the ejaculate and possible postcopulatory consequences on female behavior.     

Environmental modulation of androgen levels and secondary sex characters in two populations of the peacock blenny Salaria pavo

Morphology and endocrinology were studied in two populations of the peacock blenny Salaria pavo, with different regimes of sexual selection imposed by differences in nest site availability. The peacock blenny is a small, sexually dimorphic benthic fish that presents exclusive paternal care of the clutch and inhabits rocky shores of the Mediterranean and adjacent Atlantic areas. In a population from the Gulf of Trieste (Northern Adriatic sea) inhabiting rocky shores where nest sites are abundant, male-male competition for nests is low, males court females and a low frequency of alternative reproductive tactics (small, parasitic female-mimicking sneaker males that change tactic into nest holders in subsequent breeding seasons) occurs. Conversely at Ria Formosa, a coastal lagoon in Southern Portugal, where nest sites are scarce and highly aggregated, male-male competition for nests is very high, there is sex-role reversal with female courtship and a high frequency of alternative reproductive tactics is observed. Concomitantly, at Ria Formosa nest holder males are larger and present more developed secondary sex characters and higher levels of 11KT than at the Gulf of Trieste. However, the gonads of nest holders and parasitic males were larger in the Gulf of Trieste population. Competition for nests at Ria Formosa seems to promote more developed secondary sex characters in nest site scarcity conditions, while competition for females at the Gulf of Trieste seems to be spurring sperm competition among males in populations where nest sites are more abundant. 11KT was thus associated with the development and expression of secondary sex characters in contrasting environments. These results exemplify how the modulation of behavioral plasticity and secondary sex characters by the social environment can be mediated by androgens.     

Size breeds success: multiple paternity, multivariate selection and male semelparity in a small marsupial, Antechinus stuartii

Mating in the marsupial genus Antechinus is a synchronous annual event that is characterized by monoestry in females and abrupt postmating mortality in males. Male semelparity (multiple copulations during a single breeding season per lifetime) is often assumed to occur as a consequence of the intense mating effort expended by males in the rut, but the forces selecting for this remain elusive. Here, we investigate selection in male brown antechinus, Antechinus stuartii, and test two hypotheses for the evolution of semelparity: intermale competition and sperm competition. If intermale competition drives semelparity, we predicted that males would be under strong selection for large body size. If sperm competition is important, we predicted that selection would be strongest on scrotal size, a surrogate for testes volume. Using microsatellite markers, we found that 92% of females in free-living conditions mated with multiple males, producing litters of eight that had up to four fathers. These observations confirm the potential for sperm competition. Using selection analysis, we then found paternity success in 119 males to be related most strongly to body mass and scrotal size, thus providing support for both hypotheses. Large males presumably experience increased paternity success by gaining more matings or prolonged copulations via mate guarding, while large testes may allow increased sperm investment per copulation. Increased levels of free corticosteroid hormones in males facilitate the extreme mating effort during the short period of rut, but lead to immune suppression and consequently to the phenomenon of postmating mortality.     

The dorsal paracloacal gland and its relationship with seasonal changes in cutaneous scent gland morphology and plasma androgen in the marsupial sugar glider (Petaurus breviceps; Marsupialia: Petauridae)

A study spanning two breeding seasons was carried out to examine changes in the size of the dorsal paracloacal glands and testes in the marsupial sugar glider Petaurus breviceps Waterhouse 1839. These changes were related to seasonal increases in the plasma testosterone concentration and to morphological changes in the frontal and gular cutaneous scent glands of males.
Both dorsal paracloacal glands and testes underwent a seasonal cycle of development which reached its maximum during the June-September breeding season. These changes coincided with an increase in the plasma testosterone concentration and with the increase in activity of certain cell types within the frontal and gular glands.
Castration caused a significant decrease in the size of the dorsal paracloacal glands, while androgen replacement was effective in restoring the glands to their pre-castration size thus demonstrating the influence of androgens upon the activity of these glands.
The synchronization which exists between plasma testosterone concentration, cutaneous scent gland morphology and the size of the dorsal paracloacal glands of males, suggests that the dorsal paracloacal glands, or more likely their secretions, are important in social organization in this species.