Communal Egg-laying In Reptiles And Amphibians: Evolutionary Patterns And Hypotheses

Abstract

Communal egg-laying is widespread among animals, occurring in insects, mollusks, fish, amphibians, reptiles, and birds, just to name a few. While some benefits of communal egg-laying may be pervasive (e.g., it saves time and energy and may ensure the survival of mothers and their offspring), the remarkable diversity in the life histories of the animals that exhibit this behavior presents a great challenge to discovering any general explanation. Reptiles and amphibians offer ideal systems for investigating communal egg-laying because they generally lack parental care--a simplification that brings nest site choice behavior into sharp focus. We exhaustively reviewed the published literature for data on communal egg-laying in reptiles and amphibians. Our analysis demonstrates that the behavior is much more common than previously recognized (occurring in 481 spp.), especially among lizards (N = 255 spp.), where the behavior has evolved multiple times. Our conceptual review strongly suggests that different forces may be driving the evolution and maintenance of communal egg-laying in different taxa. Using a game theory approach, we demonstrate how a stable equilibrium may occur between solitary and communal layers, thus allowing both strategies to co-exist in some populations, and we discuss factors that may influence these proportions. We conclude by outlining future research directions for determining the proximate and ultimate causes of communal egg-laying.

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

“…It is clear that the number of eggs found in the first observation in Algonquin Provincial Park came from more than one female, so this likely is an instance of communal oviposition. It is estimated that 7% of salamanders of the family Plethodontidae exhibit this behaviour, but it is under-reported because of the difficulty in finding salamander eggs (Doody et al 2009). Two-lined salamanders typically deposit eggs on the undersides of stones or other debris in streams, with females remaining with the clutch, defending them from predators (Petranka 1998).…”

“…The best oviposition sites have obvious benefits, such as high hatching success and proximity to good natal habitat (Refsnider and Janzen 2010). Other adaptive factors such as female survivorship and reduced risk of predation of a particular female's eggs may also influence the frequency of communal nesting in salamanders (Doody et al 2009). In a review of communal oviposition in reptiles and amphibians, (Doody et al 2009) explained that some species are more likely to oviposit where another female has previously oviposited and hatched young.…”

“…Other adaptive factors such as female survivorship and reduced risk of predation of a particular female's eggs may also influence the frequency of communal nesting in salamanders (Doody et al 2009). In a review of communal oviposition in reptiles and amphibians, (Doody et al 2009) explained that some species are more likely to oviposit where another female has previously oviposited and hatched young. To my knowledge, this is the first reported case of communal oviposition of E. bislineata in Ontario.…”

Evolution of Conspecific Brood Parasitism versus Cooperative Breeding as Alternative Reproductive Tactics

“…These conflicts over costs of parental care and benefits of reproductive skew are often considered in isolation, but simultaneous conflict over parental care and reproductive skew is present in a variety of cooperatively breeding societies. This dual form of conflict includes societies with reproductive sharing as well as those with helpers (i.e., nonreproducing individuals that contribute to offspring care) and has been observed in birds, amphibians, fish, reptiles, and insects (Wilson 1975;Brown 1987;Cockburn 1998;CluttonBrock 2002;Zink 2003;Taborsky 2009;Doody et al 2009). …”

Oviposition site selectivity of some stream-dwelling caddisflies

“…Such aggregations have been observed in diverse groups of aquatic insects, including some caddisflies (Hoffmann & Resh, 2003;Reich & Downes, 2003b), mayflies (Encalada & Peckarsky, 2006;Lancaster et al, 2010) and black flies (Muirhead-Thomson, 1956;Coupland, 1991), and this behaviour is often called communal egg-laying, regardless of whether multiple females oviposit simultaneously (Doody et al, 2009). [Note, communal egg-laying involves multiple individuals ovipositing close together and differs from 'egg-clustering', a term often used to describe the behaviour of single individuals that lay eggs in batches instead of one at a time (Stamp, 1980;Courtney, 1984)].…”