Premium
RECENT AND ANCIENT ASEXUALITY IN TIMEMA WALKINGSTICKS
Author(s) -
Law Jennifer H.,
Crespi Bernard J.
Publication year - 2002
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/j.0014-3820.2002.tb01484.x
Subject(s) - asexuality , biology , intraspecific competition , phylogenetic tree , evolutionary biology , parthenogenesis , asexual reproduction , population , zoology , genetics , demography , gene , human sexuality , gender studies , embryo , sociology
Determining the evolutionary age of asexual lineages should help in inferring the temporal scale under which asexuality and sex evolve and assessing selective factors involved in the evolution of asexuality. We used 416 bp of the mitochondrial COI gene to infer phylogenetic relationships of virtually all known Timema walkingstick species, including extensive intraspecific sampling for all five of the asexuals and their close sexual relatives. The asexuals T. douglasi and T. shepardii were very closely related to each other and evolutionarily young (less than 0.5 million years old). For the asexuals T. monikensis and T. tahoe , evidence for antiquity was weak since only one population of each was sampled, intraspecific divergences were low, and genetic distances to related sexuals were high: maximum‐likelihood molecular‐clock age estimates ranged from 0.26 to 2.39 million years in T. monikensis and from 0.29—1.06 million years in T. tahoe . By contrast, T. genevieve was inferred to be an ancient asexual, with an age of 0.81 to 1.42 million years. The main correlate of the age of asexual lineages was their geographic position, with younger asexuals being found further north.