Conchostracans: Living and Fossil from Chihuahua and Sonora, Mexico

Tasch, Paul; Shaffer, Bernard L.

doi:10.1126/science.143.3608.806

Cited by 10 publications

(6 citation statements)

References 4 publications

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“…We have also added known localities for many species of Eulimnadia not included in this study ( figure 2a-c). The positions of the land masses 60 mya (corresponding to inferences of Eulimnadia's origin from the fossil record; Tasch & Shaffer 1964;Chen & Shen 1981) still require large oceanic distances for eggs to disperse among continents (figure 2b). The last time period when the major land masses containing these locations were close enough for easy overland dispersal was ca 180 mya (figure 2c).…”

Section: Discussionmentioning

confidence: 99%

“…Although clam shrimp have an excellent fossil record (Tasch 1987), the exact relationship of the extant limnadiid genera to fossil Limnadiidae is uncertain (Kobayashi 1972). Tasch & Shaffer (1964) suggest that the genus Eulimnadia evolved in the late Mesozoic era (ca 65 mya), while Chen & Shen (1981) suggest that Eulimnadia evolved from the extinct genus Yunmenglimnadia that existed in the Paleogene period (24-66 mya). Thus, from fossil evidence, the genus Eulimnadia is 24-66 million years old.…”

Section: Discussionmentioning

confidence: 99%

“…One of these transitions is from dioecy to androdioecy, which Sassaman suggested occurred in the progenitor to both Eulimnadia and Limnadia. Chen & Shen (1981) suggest that Eulimnadia and Limnadia evolved from the extinct genus Yunmenglimnadia that existed in the Paleogene period (24-66 mya), while Tasch & Shaffer (1964) suggest that the genus Eulimnadia evolved in the Late Mesozoic era (ca 65 mya). If androdioecy is the predominant form of reproduction within the genus Eulimnadia, then this genus would represent the oldest clade of androdioecious organisms known (Pannell 2002), existing from 24 to 65 million years, which would indicate that androdioecy in these crustaceans is more stable than theory predicts (Lloyd 1975;Charlesworth 1984;Pannell 1997Pannell , 2002.…”

Section: Introductionmentioning

confidence: 99%

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Ancient androdioecy in the freshwater crustaceanEulimnadia

et al. 2005

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Among the variety of reproductive mechanisms exhibited by living systems, one permutationandrodioecy (mixtures of males and hermaphrodites)-is distinguished by its rarity. Models of mating system evolution predict that androdioecy should be a brief stage between hermaphroditism and dioecy (separate males and females), or vice versa. Herein we report evidence of widespread and ancient androdioecy in crustaceans in the genus Eulimnadia, based on observations of over 33 000 shrimp from 36 locations from every continent except Antarctica. Using phylogenetic, biogeographical and palaeontological evidence, we infer that androdioecy in Eulimnadia has persisted for 24-180 million years and has been maintained through multiple speciation events. These results suggest that androdioecy is a highly successful aspect of the life history of these freshwater crustaceans, and has persisted for orders of magnitude longer than predicted by current models of this rare breeding system.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ancient androdioecy in the freshwater crustaceanEulimnadia

et al. 2005

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“…Nevertheless, androdioecy is the only known form of reproduction in this genus, and a phylogenetic analysis suggests that androdioecy is the ancestral mode of reproduction for this genus (Weeks and others 2006). The genus Eulimnadia is thought to have arisen in either the Paleogene (Chen and Shen 1981) or Cretaceous periods (Tasch and Shaffer 1964), but a biogeographic comparison suggests the genus arose up to 180 mya (Weeks and Weeks andothers (1999, 2000); Weeks and Bernhardt (2004) Estimates are from 2 populations: one from Las Cruces, New Mexico (NM) and one Portal, Arizona (AZ). Where a range of estimates have been estimated, the highest and lowest estimates are presented.…”

Section: Crustaceans In the Genus Eulimnadiamentioning

confidence: 99%

When males and hermaphrodites coexist: a review of androdioecy in animals

Weeks¹

2006

Integrative and Comparative Biology

154

142

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Androdioecy (populations consisting of males and hermaphrodites) is a rare mating system in plants and animals: up to 50 plants and only 36 animals have been described as being androdioecious, with most of the latter being crustaceans. To date, a thorough comparative analysis of androdioecy in animals has not been undertaken. Herein we present such an analysis. Androdioecy has only been extensively surveyed in 2 animal taxa: the nematode Caenorhabditis and the clam shrimp Eulimnadia. The other major taxon having androdioecious species is the Cirripedia (barnacles), but there are only limited studies on androdioecy in this group. In animals, androdioecy is found either in species that have morphologically and ecologically distinct sexes (that is, hermaphrodites and small, "complemental" males) that are derived from hermaphroditic ancestors (that is, the barnacles) or in species that have similarly-sized males and hermaphrodites that have been derived from dioecious ancestors (the remaining androdioecious species). We suggest that the barnacles have evolved a sexual specialization in the form of these complemental males that can more efficiently use the constrained habitats that these barnacles often experience. For the remaining species, we suggest that androdioecy has evolved as a response to reproductive assurance in species that experience episodic low densities. Additionally, we hypothesize that the development of mechanisms allowing reproductive assurance in species with a number of sexually differentiated traits is most likely to result in androdioecy rather than gynodioecy (mixtures of females and hermaphrodites), and that these species may be developmentally constrained to stay androdioecious rather than being capable of evolving into populations solely consisting of efficient, self-compatible hermaphrodites. We conclude by suggesting several areas in need of further study to understand more completely the evolution and distribution of this interesting mating system in animals.

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“…The large female valves of this species would be assigned to Limnadia and the smaller male valves to Eulimnadia, yet they are dimorphs of the same species. (For other data on living Eulimnadia see Tasch and Shaffer, [1964].) (Tasch in Tasch and Jones, 1979b).…”

Section: Palaeolimnadia (Palaeolimnadia) Wianamattensismentioning

confidence: 99%