@article {344,
	title = {Multiple origins of eusociality among sponge-dwelling shrimps (Synalpheus)},
	journal = {Evolution},
	volume = {54},
	number = {2},
	year = {2000},
	note = {Article.0014-3820English},
	month = {April},
	pages = {503-516},
	abstract = {As the most extreme expression of apparent altruism in nature, eusociality has long posed a central paradox for behavioral and evolutionary ecology. Because eusociality has arisen rarely among animals, understanding the selective pressures important in early stages of its evolution remains elusive. Employing a historical approach to this problem, we used morphology and DNA sequences to reconstruct the phylogeny of 13 species of sponge-dwelling shrimps (Synalpheus) with colony organization ranging from asocial pair-bonding through eusociality. We then used phylogenetically independent contrasts to test whether sociality was associated with evidence of enhanced competitive ability, as suggested by hypotheses invoking an advantage of cooperation in crowded habitats. The molecular, morphological, and combined data each strongly supported three independent origins of monogynous, multigenerational (eusocial) colony organization within this genus. Phylogenetically independent contrasts confirmed that highly social taxa, with strong reproductive skew, have significantly higher relative abundance within the host sponge than do less social taxa, a result that was robust to uncertainty in tree topology and varying models of character change. A similar tendency for highly social species to share their sponge with fewer congener species was suggestive, but not significant. Because unoccupied habitat appears to be limiting for many sponge-dwelling shrimp species, these data are consistent with hypotheses that cooperative social groups enjoy a competitive advantage over less organized groups or individuals, where independent establishment is difficult, and that enemy pressure is of central importance in the evolution of animal sociality.},
	keywords = {[01500] Evolution, [07003] Behavioral biology - Animal behavior, [07502] Ecology: environmental biology - General and methods, [64054] Invertebrata:comparative, [75112] Malacostraca, altruism, Animalia, Arthropoda, Arthropods, asocial pair-bonding, Behavior, colony organization: monogynous, Crustacea, Crustaceans, dna, eusociality, Evolution and Adaptation, experimental morphology, Invertebrata, Invertebrates, Malacostraca: Animals, Morphology, multigenerational, multiple origins, phylogeny, physiology and pathology - Arthropoda: crustacea, social evolution, Synalpheus [Malacostraca]},
	url = {file://localhost/Users/kristinhultgren/Desktop/Papers/Duffy_Morrison_Rios_2000.pdf},
	author = {Duffy, J. E. and Morrison, C. L. and Rios, Ruben}
}
@article {407,
	title = {Colony defense and behavioral differentiation in the eusocial shrimp Synalpheus regalis},
	journal = {Behavioral Ecology and Sociobiology},
	volume = {51},
	number = {5},
	year = {2002},
	month = {Apr},
	pages = {488-495},
	abstract = {The sponge-dwelling shrimp Synalpheus regalis and several congeners exhibit monogynous, eusocial colony structures, and field data suggest that these social species may have a competitive advantage in crowded environments. We explored mechanisms of colony defense, a likely contributor to such a social advantage, by measuring responses of resident shrimp to conspecific and heterospecific intruders in experimental nests. To test for behavioral differentiation among classes of individuals, we compared responses of juvenile, large male, and breeding female (queen) S. regalis to each intruder type. Colony residents discriminated nestmates from both foreign conspecific and heterospecific intruders, making more aggressive snaps and fewer contacts with such intruders than with controls from the same colony. S. regalis colonies also exhibited behavioral differentiation among classes of individuals: most snaps against intruders were by large males. Thus, large males defended the colony, allowing juveniles and the queen to feed and grow unmolested. On a per-individual basis, intruders more frequently contacted the queen than either large males or juveniles, possibly indicating that signals from the queen provide information about colony status as they do in many social insects. Sampling of unmanipulated field colonies showed that colony reproductive output increased linearly, by a factor of 177 times, throughout the range in sampled colony sizes (2-356 individuals), whereas average per capita reproductive output decreased by only 61\% over the same range. These data suggest that non-breeding colony members may gain inclusive fitness benefits by remaining in and helping defend the natal sponge. Differentiation among individuals in reproductive and defensive behavior may enhance the efficiency and productivity of S. regalis colonies and contribute to their apparent competitive advantage over less social congeners.},
	url = {<Go to ISI>://000175495300012},
	author = {Duffy, J. E. and Morrison, C. L. and Macdonald, K. S.}
}
@article {329,
	title = {Phylogenetic evidence for an ancient rapid radiation of Caribbean sponge-dwelling snapping shrimps (Synalpheus)},
	journal = {Molecular Phylogenetics \& Evolution},
	volume = {30},
	number = {3},
	year = {2004},
	note = {Article.1055-7903 (ISSN print)English},
	month = {March},
	pages = {563-581},
	abstract = {A common challenge in reconstructing phylogenies involves a high frequency of short internal branches, which makes basal relationships difficult to resolve. Often it is not clear whether this pattern results from insufficient or inappropriate data, versus from a rapid evolutionary radiation. The snapping shrimp genus Synalpheus, which contains in excess of 100 species and is a prominent component of coral-reef faunas worldwide, provides an example. Its taxonomy has long been problematic due to the subtlety of diagnostic characters and apparently widespread variability within species. Here we use partial mt COI and 16S rRNA sequences and morphological characters to reconstruct relationships among 31 species in the morphologically well-defined gambarelloides species group, a putative clade of obligate sponge associates that is mostly endemic to the Caribbean and contains the only known eusocial marine animals. Analysis of the combined data produced a single tree with good support for many terminal clades and for relationships with outgroups, but poor support for branches near the base of the gambarelloides group. Most basal branches are extremely short and terminal branches are long, suggesting a relatively ancient, but rapid radiation of the gambarelloides group. This hypothesis is supported by significant departure from a null model of temporally random cladogenesis. Calibration of divergence times among gambarelloides-group species using data from three geminate pairs of Synalpheus species separated by the isthmus of Panama suggests a major radiation between apprx5 and 7 Mya, a few My before final closure of the Panamanian seaway during a period of spreading carbonate environments in the Caribbean; a second, smaller radiation occurred apprx4 Mya. This molecular evidence for a rapid radiation among Caribbean marine organisms in the late Miocene/early Pliocene is strikingly similar to patterns documented from fossil data for several other Caribbean reef-associated invertebrate taxa. The similar patterns and timing of cladogenesis evidenced by molecular and fossil data for different Caribbean and East Pacific taxa suggests that the radiation involved a wide range of organisms, and strengthens the case that poor basal resolution in the gambarelloides group of Synalpheus reflects a real evolutionary phenomenon. The rapid radiation also helps explain the historical difficulty of diagnosing species in Synalpheus.},
	keywords = {16S rRNA sequences, adaptive radiation},
	author = {Morrison, C. L. and Rios, R. and Duffy, J. E.}
}
