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Tempo, mode and phylogenetic associations of relative embryo size evolution in angiosperms.
J Evol Biol 2006; 19(2):625-34JE

Abstract

Relative embryo size (E : S, the ratio of embryo to seed) is a key trait related to germination ecology and seed plant evolution. A small, underdeveloped embryo is a primitive feature of angiosperms, which has led to the hypothesis that an evolutionary trend towards increasing E : S has occurred. Here, I examine first the tempo and mode of E : S evolution in angiosperms; then I test for phylogenetic associations of E : S with traits hypothetically related to anagenetic (germination time) and cladogenetic (number of species per family and differential speciation) change, and finally I test the existence of a directional increasing trend in E : S. The analysis of the evolutionary tempo suggests that E : S changed very fast early in evolutionary time and remained stable later, which is consistent with early radiations and fits well with the history of angiosperms consisting of rapid spread associated with great diversification rates soon after their origin. E : S evolution in angiosperms has not followed a punctuational mode of evolution but a scaled-gradualism evolution in which stasis has occurred in longer branches of the phylogeny. An evolutionary trend towards increasing E : S has not been actively driven by anagenesis nor cladogenesis, although large E : S is associated with high levels of diversification (i.e. number of species per family). This rapid ecological diversification occurring in the early radiation probably produced an increasing phenotypic variance in the E : S. Because the ancestral embryo was so small, an increase in variance might have produced a passive trend towards the only direction allowed for the ancestral embryo to evolve. Thus, a passive diffusion away from a lower bound may explain the average increase in E : S.

Authors+Show Affiliations

Centro de Investigaciones sobre Desertificación (CSIC-UV-GV), Apartado Oficial, Albal, Valencia, Spain. Miguel.Verdu@uv.es

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16599937

Citation

Verdú, M. "Tempo, Mode and Phylogenetic Associations of Relative Embryo Size Evolution in Angiosperms." Journal of Evolutionary Biology, vol. 19, no. 2, 2006, pp. 625-34.
Verdú M. Tempo, mode and phylogenetic associations of relative embryo size evolution in angiosperms. J Evol Biol. 2006;19(2):625-34.
Verdú, M. (2006). Tempo, mode and phylogenetic associations of relative embryo size evolution in angiosperms. Journal of Evolutionary Biology, 19(2), pp. 625-34.
Verdú M. Tempo, Mode and Phylogenetic Associations of Relative Embryo Size Evolution in Angiosperms. J Evol Biol. 2006;19(2):625-34. PubMed PMID: 16599937.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Tempo, mode and phylogenetic associations of relative embryo size evolution in angiosperms. A1 - Verdú,M, PY - 2006/4/8/pubmed PY - 2006/6/24/medline PY - 2006/4/8/entrez SP - 625 EP - 34 JF - Journal of evolutionary biology JO - J. Evol. Biol. VL - 19 IS - 2 N2 - Relative embryo size (E : S, the ratio of embryo to seed) is a key trait related to germination ecology and seed plant evolution. A small, underdeveloped embryo is a primitive feature of angiosperms, which has led to the hypothesis that an evolutionary trend towards increasing E : S has occurred. Here, I examine first the tempo and mode of E : S evolution in angiosperms; then I test for phylogenetic associations of E : S with traits hypothetically related to anagenetic (germination time) and cladogenetic (number of species per family and differential speciation) change, and finally I test the existence of a directional increasing trend in E : S. The analysis of the evolutionary tempo suggests that E : S changed very fast early in evolutionary time and remained stable later, which is consistent with early radiations and fits well with the history of angiosperms consisting of rapid spread associated with great diversification rates soon after their origin. E : S evolution in angiosperms has not followed a punctuational mode of evolution but a scaled-gradualism evolution in which stasis has occurred in longer branches of the phylogeny. An evolutionary trend towards increasing E : S has not been actively driven by anagenesis nor cladogenesis, although large E : S is associated with high levels of diversification (i.e. number of species per family). This rapid ecological diversification occurring in the early radiation probably produced an increasing phenotypic variance in the E : S. Because the ancestral embryo was so small, an increase in variance might have produced a passive trend towards the only direction allowed for the ancestral embryo to evolve. Thus, a passive diffusion away from a lower bound may explain the average increase in E : S. SN - 1010-061X UR - https://www.unboundmedicine.com/medline/citation/16599937/Tempo_mode_and_phylogenetic_associations_of_relative_embryo_size_evolution_in_angiosperms_ L2 - https://doi.org/10.1111/j.1420-9101.2005.00998.x DB - PRIME DP - Unbound Medicine ER -