Communal Oviposition Research Articles

A sex-specific switch between visual and olfactory inputs underlies adaptive sex differences in behavior

SummaryAlthough males and females largely share the same genome and nervous system, they differ profoundly in reproductive investments and require distinct behavioral, morphological, and physiological adaptations. How can the nervous system, while bound by both developmental and biophysical constraints, produce these sex differences in behavior? Here, we uncover a novel dimorphism in Drosophila melanogaster that allows deployment of completely different behavioral repertoires in males and females with minimum changes to circuit architecture. Sexual differentiation of only a small number of higher order neurons in the brain leads to a change in connectivity related to the primary reproductive needs of both sexes—courtship pursuit in males and communal oviposition in females. This study explains how an apparently similar brain generates distinct behavioral repertoires in the two sexes and presents a fundamental principle of neural circuit organization that may be extended to other species.

Communal oviposition of the Cuban tree snail Polymita muscarum (Gastropoda: Cepolidae) in an agroecosystem

Communal oviposition remains to be convincingly shown in terrestrial gastropods. The present study reports data on communal oviposition of a threatened tree snail, Polymita muscarum, in a Cuban agroecosystem from Yaguajay, Banes municipality, Holguín province, in a fixed plot of 119 m2. Between 2011 and 2012, we took data on oviposition site microhabitats, the number of snails/nest and the number of ovipositions/day. We found communal oviposition involving between two and 20 individuals. Usually the oviposition took place underground, at the base of trees and shrubs, between the roots. This study indicates the potential value of understanding behavioral ecology in order to better support conservation programs.

Interspecific communal oviposition by the native Puerto Rican Eyespotted Geckolet (Sphaerodactylus macrolepis) and invasive House Gecko (Hemidactylus sp.) in Puerto Rico

Interspecific communal oviposition by the native Puerto Rican Eyespotted Geckolet (Sphaerodactylus macrolepis) and invasive House Gecko (Hemidactylus sp.) in Puerto Rico

Olympic Torrent Salamander (Rhyacotriton olympicus) Oviposition Site With Notes On Early Development

We describe the eggs, oviposition site, and pre-hatching development of the Olympic Torrent Salamander (Rhyacotriton olympicus) for the first time. We made field observations before oviposition and continued them until the site washed out. We also reared an egg to hatching in the laboratory to allow us to describe early development. Oviposition is similar to that of the other 3 torrent salamander species in that unattached eggs are deposited separately in the interstices of an unconsolidated coarse-clast substrate through which water flows. The number of eggs (n = 10) at this oviposition site falls within the range of variability ascribed to single clutches for other torrent salamander species (n = 5–11). However, haphazard dispersion of deposited eggs, likely typical, and sometimes communal oviposition sites, can create ambiguity in what comprises 1 clutch. Egg capsules averaged 9.5 mm ± 0.9 mm SD (range: 8.0–11.0 mm); their pale yellow-white ova, measured when still roughly round, averaged 4.5 mm ± 0.5 mm SD (range: 4.0–5.0 mm). Lack of attachment may constrain torrent salamander egg deposition to low-flow habitats, which appear more frequent in headwater landscapes. Colluvium, also frequent in headwater landscapes, may often provide the low-flow interstitial matrix ideal for torrent salamander oviposition.

Identification of communal oviposition pheromones from the black fly Simulium vittatum.

The suite of pheromones that promote communal oviposition by Simulium vittatum, a North American black fly species, was identified and characterized using gas chromatography-mass spectrometry, electrophysiological, and behavioral bioassays. Behavioral assays demonstrated that communal oviposition was induced by egg-derived compounds that were active at short range and whose effect was enhanced through direct contact. Three compounds (cis-9-tetradecen-1-ol, 1-pentadecene, and 1-tridecene) were identified in a non-polar solvent extract of freshly deposited S. vittatum eggs that were capable of inducing the oviposition response. Electroantennography demonstrated that two of these three compounds (1-pentadecene and 1-tridecene) actively stimulated antennal neurons. Identification of the oviposition pheromones of this family may be helpful in developing control measures for nuisance black flies and for medically-important species such as Simulium damnosum sensu lato.

EVIDENCE OF COMMUNAL OVIPOSITION AND NEST ABANDONMENT IN THE NORTHERN TWO-LINED SALAMANDER (EURYCEA BISLINEATA, (GREEN, 1818)) IN NORTHEASTERN CONNECTICUT

Most plethodontid salamanders oviposit their eggs in an individual nest and attend the clutch until hatching. Here, we describe aspects of the reproduction of Eurycea bislineata (Northern Two-lined Salamander) from three field sites in northeastern Connecticut that contrast with the typical plethodontid reproductive behavior. Rocks used as oviposition sites contained up to 296 eggs, with an average of more than 100. These numbers exceed the maximum ovarian egg counts for this species, indicating that communal oviposition is common. The lack of correlation between rock size and number of eggs, as well as the lack of discrete clutches when eggs are laid in large clusters, suggests that communal oviposition may be caused by something other than nest site limitation. Additionally, the rate of maternal attendance at nests was low. Thus, communal oviposition with high rates of nest abandonment is the dominant reproductive strategy in E. bislineata at these sites.

Communal Oviposition in the Northern Two-lined Salamander (<em>Eurycea bislineata</em>) in Algonquin Provincial Park, Ontario

While surveying a stream for amphibians in Algonquin Provincial Park, Ontario, Canada, I discovered a clutch of Two-lined Salamander (Eurycea bislineata) eggs on the underside of a partially submerged rock. I counted 165 eggs and measured them using ImageJ from a digital photograph. The quantity of eggs is far greater than any known clutch size for this species, and it was likely deposited by more than one female. This is the first report of communal oviposition in this species in Canada.

Communal Nesting and Parental Care in Oudri's Fan-Footed Gecko (Ptyodactylus oudrii): Field and Experimental Evidence of an Adaptive Behavior

Abstract Oudri's Fan-Footed Gecko (Ptyodactylus oudrii) is a common North African desert lizard that lives in dense colonies. Reproductive behavior shows a number of peculiarities in egg laying. Females select communal oviposition sites in rocky recesses at human-made structures. Individuals of both sexes perform communal parental care of the eggs. We performed field observations to analyze the extent of communal nesting in nature in southeast Morocco. We also carried out laboratory experiments to analyze the function of this behavior. In Experiment 1, we assessed whether the presence of previous clutches influenced whether females select a site for oviposition. In experiment 2, we tested whether parental egg-attendance influenced the hatching success of eggs. Finally, in Experiment 3, we compared hatching success of communal and solitary clutches under laboratory conditions. Communal nesting was the generally observed in the field. With a single exception, all clutches were restricted to one area. In 32%...

Field Observations of Oviposition and Early Development of the Coastal Tailed Frog (Ascaphus truei)

Key words: Ascaphus truei, clutch size,Coastal Tailed Frog, communal oviposition,early development, growth, Olympic Peninsula,Washington StateTailed frogs (genus Ascaphus) are stream am-phibians endemic to the Pacific Northwest (Jonesand others 2005) that are thought to represent thesister taxon of all other living anurans (Ford andCannatella 1993; Haas 2003). Among their uniquecharacteristics is their reproductive mode. Of the5912 described anuran species (AmphibiaWeb2010), the 2 species of tailed frog are the onlyanurans known to engage in copulation thatincludes intromission (Sever and others 2001).Further, the sperm storage capability of femalesallowstemporalseparationbetweenbreedingandoviposition, resulting in females depositing eggsalone (Metter 1964; Brown 1989).Knowledge of tailed frog oviposition sites,which are always concealed in streambeds, islimited (Karraker and others 2006 and referencestherein). What is known is based on theopportunistic discovery of sites during theexamination of instream substrates, a standardprocedure of various types of stream surveys (forexample, Adams 1993; Bury and others 2001).These haphazard discoveries have resulted inencountering various stages of clutch develop-ment, but have never involved field observationof oviposition. Observations of developmentfrom oviposition also have been restricted tofemales laying eggs in a laboratory via hormonalinduction (Wernz and Storm 1969; Brown 1975).Here we report the 1st field observation ofoviposition by tailed frogs, and selected fielddata on early development.Study AreaOur observations were made on Miller Creek(UTM Zone 10, 488225E, 5253553W, WGS84;elevation approximately 216 m), a 3rd-ordernon-fish-bearing stream on the east side of theOlympic Peninsula near Lake Cushman, MasonCounty, Washington. The site of our observa-tions consisted of a long riffle with steady fast-moving water. A bedrock step-pool was located5.5 m upstream and a small braided cascadewas located 5.9 m downstream of the site.Bedrock outcroppings lined the banks up- anddownstream for at least 40 m. Surroundinguplands are managed for timber production bythe Washington Department of Natural Re-sources; the local stand was last harvested in1945. Red Alder (Alnus rubra) and Vine Maple(Acer circinatum) dominate the riparian oversto-ry; understory is mostly Salmonberry (Rubusspectabilis), Devil’s Club (Oplopanax horridus),and Sword Fern (Polystichum munitum). Steephillslopes (50–65%) are blanketed with 2nd-growth Douglas-fir (Pseudotsuga menziesii),Western Hemlock (Tsuga heterophylla), andWestern Redcedar (Thuja plicata). Lithology ismostly Pleistocene age glacial till with large-clast material contributed from the basalt-basedCrescent Formation upstream.Initial Observations of OvipositionOn 29 July 2008, during rubble-rouse sam-pling (Quinn and others 2007) of a 2-m unit forstream-associated amphibians within this reach,we rolled a large (65 360 44 cm) boulder thatwas imbedded about 10 cm in surroundinggravel and sand. Four adult female A. truei andat least 183 A. truei eggs were found beneaththis boulder (Fig. 1). One female was activelylaying eggs. A spot water temperature taken atthis site at about 11:00 was 12.06C. A separategroup of 24 eggs was found beneath a 2ndboulder (55 3 40 3 24 cm) ,1 m downstreamthat was imbedded in approximately 20 cm of

Oviposition site selectivity of some stream-dwelling caddisflies

Population dynamics depends upon the spatial distribution of individuals in heterogeneous environments. The various processes surrounding insect oviposition are central to understanding their population dynamics because the choice of oviposition site ultimately influences the survivorship and spatial distribution of their progeny. Aquatic insects are often assumed to have non-selective oviposition habits, but empirical data are scarce and selective oviposition may be quite common. We quantitatively sampled egg masses of stream-dwelling caddisflies (Trichoptera) that specialise in egg-laying on hard substrata underwater, in order to characterise oviposition site selectivity and test for communal oviposition. In a field survey of two Scottish streams, we sampled egg masses of three species, Polycentropus flavomaculatus, Hydropsyche siltalai, Rhyacophila dorsalis, with the aim of testing whether egg mass abundance varied with current (riffles vs. pools), location within the channel (margins vs. centre) and rock exposure (emergent vs. fully submerged). In one stream, we captured adults landing on emergent rocks and assessed whether females were modified morphologically for swimming. The egg masses of two species (P. flavomaculatus, H. siltalai) occurred primarily on submerged rocks in pool margins, and adult females had legs modified for swimming. In contrast, egg masses of R. dorsalis were most abundant on the underside of emergent rocks in riffles, and females were not modified for swimming. Communal oviposition was evident for all three species, with most egg masses aggregated on the minority of potential rocks. How females locate oviposition sites and the consequences of these highly specialised oviposition behaviours to the survival and spatial distribution of larvae now require investigation. The effects of these behaviours on population dynamics are likely to differ from terrestrial herbivores because oviposition sites are not food resources for these aquatic species.

Beyond size-number trade-offs: clutch size as a maternal effect.

Traditionally, research on life-history traits has viewed the link between clutch size and offspring size as a straightforward linear trade-off; the product of these two components is taken as a measure of maternal reproductive output. Investing more per egg results in fewer but larger eggs and, hence, offspring. This simple size-number trade-off has proved attractive to modellers, but our experimental studies on keelback snakes (Tropidonophis mairii, Colubridae) reveal a more complex relationship between clutch size and offspring size. At constant water availability, the amount of water taken up by a snake egg depends upon the number of adjacent eggs. In turn, water uptake affects hatchling size, and therefore an increase in clutch size directly increases offspring size (and thus fitness under field conditions). This allometric advantage may influence the evolution of reproductive traits such as growth versus reproductive effort, optimal age at female maturation, the body-reserve threshold required to initiate reproduction and nest-site selection (e.g. communal oviposition). The published literature suggests that similar kinds of complex effects of clutch size on offspring viability are widespread in both vertebrates and invertebrates. Our results also challenge conventional experimental methodologies such as split-clutch designs for laboratory incubation studies: by separating an egg from its siblings, we may directly affect offspring size and thus viability.

Why do female lizards lay their eggs in communal nests?

1. In many reptile species, females oviposit communally (i.e. many clutches are laid within the same nest). This behaviour might result from constraint (scarcity of nest-sites offering suitable incubation conditions) or adaptation (direct fitness benefits accruing from the proximity of other eggs). 2. To test between these alternatives, we gathered field and laboratory data on montane scincid lizards Bassiana duperreyi from south-eastern Australia. Our data support the adaptationist hypothesis. 3. In the field, communal vs. solitary clutches were laid in similar sites, and the relative frequency of communal nesting was not predictable from nest-site availability. Thermal regimes for incubation did not differ between communal vs. solitary nests, nor between eggs at the core vs. periphery of a communal nest. In the laboratory, females selectively oviposited beside existing eggs rather than in otherwise identical potential nesting sites. 4. From cycling-temperature incubation in the laboratory, eggs incubated within a cluster of other eggs took up less water, but produced hatchlings that were larger and faster-running than were hatchlings from eggs incubated alone. 5. Hydric modifications of incubation conditions within a cluster of tightly packed eggs thus may provide a direct fitness benefit to communal oviposition.

TAXONOMIC VARIATION IN OVIPOSITION BY TAILED FROGS (ASCAPHUS SPP)

Abstract Tailed frogs (Ascaphus spp.) oviposit in cryptic locations in streams of the Pacific Northwest and Rocky Mountains. This aspect of their life history has restricted our understanding of their reproductive ecology. The recent split of A. montanus in the Rocky Mountains from A. truei was based on molecular differentiation, and comparisons of their ecology are limited. Our objectives were to provide a range-wide summary of information on Ascaphus oviposition, compare some aspects of the reproductive ecology of the 2 species, and examine geographic variation in their reproductive traits. Reproductive ecology of the 2 species differed. Ascaphus truei had smaller clutches, oviposited later in the summer, and had a longer duration of oviposition than A. montanus. A greater number of communal oviposition sites were attributed to A. montanus. These ecological differences support the recent taxonomic revision of Ascaphus and suggest that different management strategies may be necessary for each species whe...

The dynamics of brood desertion among communally breeding females in the treehopper, Publilia concava

In species that exhibit extended parental care, females sometimes lay eggs communally in order to redistribute the costs of offspring care. Communal egg-laying often involves redundancy in female effort, such that the number of females contributing to reproduction is more than is needed to provide adequate parental care. As a result, a subset of females will often abandon the communal brood, with the time of departure ranging from immediate abandonment after egg-laying (brood parasitism) to delayed abandonment with prolonged care (cooperative breeding). In this paper I approach the parental care dynamics of female-female broods as a desertion game similar to that of mate desertion in species with bi-parental care. I describe a field study of the insect Publilia concava (Hemiptera: Membracidae), a species that exhibits communal oviposition and a full range of egg guarding. This species exhibits full redundancy in female care, with no difference in survival between singly and doubly guarded broods. I find that double guarding is extremely rare in the population, with most communal broods having only one female guard. While this guard was usually the female that initiated the brood, these same females were more likely to abandon when secondary females arrived and when secondary females exhibited longer guarding durations. Paradoxically, the secondary females usually abandoned the broods they visited, resulting in up to 50% of broods with double abandonment. These unguarded broods suffered a 50% reduction in hatching success, reflecting an important risk for primary females that abandon egg masses to secondary females. Overall, P. concava exhibits desertion dynamics similar to mate desertion in vertebrates and it is likely that the theoretical work in this area will be useful for future work that addresses the allocation of parental care among communal breeders.

Demography and reproductive ecology of the Columbia spotted frog (Rana luteiventris) across the Palouse

Here we report on the demography and reproductive ecology of the Columbia spotted frog (Rana luteiventris Thompson, 1913) breeding in ponds across the Palouse Bioregion of Washington and Idaho. Spotted frogs are unusual, if not unique, among temperate ranids in that males establish the oviposition site before females become active. Females laid at one or two communal sites in shallow water. Our breeding populations were small, never exceeding 50 adults counted, and most displayed male-biased sex ratios. We estimated effective population sizes (Ne) as ranges determined by extremes in male breeding success; these varied between 3.2 and 37.8. Even the latter falls below the minimum required for long-term population viability. Small population size may make spotted frogs vulnerable to genetic problems and environmental insults. Communal oviposition certainly renders a population's reproductive effort vulnerable to variation in hydroperiod, which we observed during the dry spring of 2004. In the absence of information on the degree of "connectedness" among our ponds as subunits of more resilient metapopulations, we suggest that small population size and communal oviposition likely render R. luteiventris vulnerable to anthropogenic disturbance. Furthermore, the status of R. luteiventris on the Palouse may be less secure than assumed currently.

Effect of substrate availability and conspecific cues on communal oviposition in the apple murex snail Phyllonotus pomum

Communal oviposition, the sharing of a single substrate by conspecific individuals for depositing clutches of egg capsules, is common among gastropod molluscs. In soft-bottom habitats, communal oviposition may occur because of a limitation of suitable hard substrate. Conspecific cues may be responsible for aggregating females. This study examined the oviposition behavior of the apple murex snail Phyllonotus pomum in seagrass beds in St. Joseph's Bay, Florida. Movement pat- terns obtained from a mark-recapture study conducted during the 5 mo prior to egg-laying season suggest that females are capable of moving, and often move, farther than the distance at which sub- strate might become limiting. In field surveys, 1 to greater than 14 possible suitable substrates were available within a 4 m radius of communal oviposition events, yet females still oviposited commu- nally. In a caged field-substrate manipulation experiment, females contributed to a single communal egg-mass even when additional substrates were available within 0.25 m. When given a choice between substrate without and with fresh egg capsules (< 8 d old) in a caged field experiment, females deposited an equal number of clutches on each type of substrate. Communal oviposition in P. pomum was not mediated by substrate limitation, and previously laid conspecific egg capsules did not attract females or induce them to oviposit communally. Alternatively, there may be an adaptive advantage to communal oviposition in P. pomum. It is possible that the process of egg-laying from 1 individual attracts, aggregates and induces oviposition in neighboring females.

Interspecific communal oviposition and reproduction of four species of lizards (Sauria: Gekkonidae) in the lower Florida Keys

Interspecific communal oviposition and reproduction of four species of lizards (Sauria: Gekkonidae) in the lower Florida Keys

Communal Oviposition and Lack of Parental Care in Batrachoseps nigriventris (Caudata: Plethodontidae) with a Discussion of the Evolution of Breeding Behavior in Plethodontid Salamanders

Although plethodontid salamanders are characterized by a diversity of life histories, several aspects of their breeding biology are highly conserved. Two of these are solitary oviposition and attendance of clutches by females until hatching. We infer evolutionary changes in these reproductive features based on the discovery of oviposition sites and eggs of two species, Batrachoseps nigriventris and B. wrighti. Batrachoseps nigriventris deviates from the ancestral reproductive pattern in two ways: most clutches are laid at communal oviposition sites and female care has been lost. In contrast, B. wrighti may deviate from the ancestral pattern only in the loss of maternal care. A review of the reproductive biology of Batrachoseps and other plethodontids reveals that female attendance of eggs was lost in the ancestor of all Batrachoseps, whereas communal oviposition likely originated following the basal split within the genus. Additionally, communal oviposition and abandonment of clutches have evolved in two other plethodontid clades: Nototriton/Oedipina and Hemidactylium. Studies of taxa that have lost parental care may give insight into factors favoring the maintenance of parental care in other lineages. LETHODONTID salamanders are characterized by a diversity of life histories, in

Oviposition pheromone in the Simulium damnosum complex: biological activity of chemical fractions from gravid ovaries

Abstract. Communal oviposition in the Afrotropical blackfly species complex Simulium damnosum Theobald (Diptera: Simuliidae) is mediated by a pheromone emitted by freshly laid eggs. Previously, two compounds (designated peaks A and B) emanating from fresh eggs were shown to be associated with attractiveness to gravid blackflies in bioassay. The present study investigated the role of these compounds by testing the responses of wild‐caught Simulium yahense in Ghana to fractionated hexane extracts of gravid ovaries prepared by gas chromatography (GC). Although the fractions were prepared from Sierra Leonean Simulium leonense, GC analysis of the emissions from fresh S.yahense eggs showed that the volatile blends of both species were similar. When tested in a two‐choice bioassay, 66% of ovipositing blackflies chose the substrate baited with a mixture of the four fractions recombined. In a series of bioassays testing responses to the four individual fractions presented with a control in a multiple‐choice arrangement, only fraction 3 (containing peaks A and B) attracted significantly more ovipositions than the other fractions and control. However, fraction 3 failed to elicit a significant response when presented as the sole attractant with a control in a two‐choice bioassay. It was concluded that fraction3, though mainly responsible for mediating aggregated oviposition by S.yahense, was acting in tandem with additional cues, probably further chemicals, which remain to be isolated and characterized.

Oviposition aggregation pheromone in the Simulium damnosum complex

Communal oviposition by the Simulium damnosum complex of Afrotropical blackflies (Diptera: Simuliidae) was investigated under controlled laboratory conditions, using wild-caught flies in Sierra Leone. Volatile compounds emitted by Simulium eggs were trapped using a closed collection system, and their attractiveness to gravid flies was tested in a two-choice behavioural bioassay. Significantly more female blackflies oviposited on substrates baited with freshly laid eggs (100% chose the baited substrate), or with the volatiles collected from freshly laid eggs (85% chose the baited substrate), in preference to the relevant control substrates. Substrates baited with volatiles from 12-h-old eggs were not significantly more attractive than controls (only 31% chose the baited substrates; P = 0.33). Gas chromatographic analysis of the egg volatiles consistently showed two peaks emanating from fresh eggs, but significantly lower amounts from 12-h-old eggs (P < 0.05). A novel system for collecting the volatiles from this and other blackfly species, as they laid eggs on a substrate in flowing water, is described. Volatiles collected using this method showed identical gas chromatographic profiles to those of fresh eggs alone, indicating that the flies themselves produced no other volatile chemical signals during oviposition. Evidently communal oviposition by S. damnosum s.l. was mediated by a pheromone emanating from fresh eggs. The role of pheromone-mediated egg aggregation in blackfly ecology is discussed, and its possible manipulation is considered.