| Presentation Detail
Life History Studies Whelan, Nathan [1]. Modeling life history evolution of a critically imperiled family of freshwater gastropods. Freshwater gastropods of the family Pleuroceridae have one of the highest imperilment rates of any species rich family in North America (79%). Pleurocerids are the focus of numerous state and federal recovery plans, but management plans are hampered by a general lack of information concerning species specific life history strategies. Furthermore, how different egg-laying behaviors of pleurocerids have evolved is entirely unknown. Using a captive propagation environment, we documented the egg laying strategies of representative species from each extant pleurocerid genus and species from across the family’s geographic range. To create a framework for testing hypotheses of life history evolution, a coalescent based (4 gene) species tree was inferred in *BEAST using multiple individuals per species. Ancestral state reconstruction of pleurocerid egg-laying behaviors was performed with Bayes Traits, and 500 trees sampled from the posterior distribution of each *BEAST run were used to account for species tree uncertainty. Pleurocerids were found to lay eggs in four different patterns: 1) circular clutch; 2) large strip clutches; 3) single eggs; 4) single egg lines. These behaviors were species specific since no variation in the pattern of egg deposition was observed within species. The most recent common ancestor of all pleurocerids was inferred to lay eggs singly, which indicates a general pattern of single egg-laying evolving into more “complex” behaviors that involve laying eggs in clutches that incorporate large amounts of mucus and external organic matter. Interestingly, clutch laying behaviors have evolved multiple times within Pleuroceridae and it appears that reversals from clutch egg-laying to single eggs or single egg lines, does not occur. Conversely, in lineages that evolved the behavior of laying single egg lines, reversals back to laying single eggs are common. Convergent evolution of clutch egg-laying behaviors seen in pleurocerids is notable, and it may have facilitated diversification of pleurocerid lineages. Furthermore, the absence of reversals from a clutch laying behavior back to laying single eggs in conjunction with clearly greater parental investment in depositing clutches indicates that clutch laying may be selectively advantageous for freshwater gastropods. Understanding the evolution of pleurocerid egg-laying behaviors and other life history strategies will aid in developing conservation strategies that take into account both the evolutionary trajectory of pleurocerids and possible selective pressures these snails faced in the past.
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1 - University of Alabama, Biological Sciences, Box 870345, Tuscaloosa, AL, 35487, USA
Keywords:
Life history
ancestral state reconstruction
gastropod
species tree
freshwater
conservation.
Presentation Type: Regular Oral Presentation
Session: 136
Location: Alpine C/Snowbird Center
Date: Tuesday, June 25th, 2013
Time: 11:00 AM
Number: 136003
Abstract ID:576
Candidate for Awards:W.D. Hamilton Award for Outstanding Student Presentation |
