Macroevolution by Emanuele Serrelli & Nathalie Gontier

Author:Emanuele Serrelli & Nathalie Gontier
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

4.3 Evolutionary Patterns

The history of life on Earth is characterized by a combination of unique and repeated events. An evolutionary pattern is an empirically discernible regularity in the history of a biological system. As such, the elements of a pattern recur in a predictable manner. A great many evolutionary patterns are recognized for classes of individuals at different levels of biological hierarchies, although some patterns appear to be isomorphic across levels (such as trends for increasing complexity; e.g., McShea and Brandon 2010).

There are two fundamental categories of historical patterns: diversity and disparity patterns. Diversity patterns describe the dynamics of change in the quantity of evolving individuals at a given level of a genealogical hierarchy. They are the product of the origin and death dynamics among individuals. Most studies have focused on three kinds of rates of evolution: rates of morphological evolution, rates of taxic evolution, and rates of genomic evolution (Raup 1987; Schoch 1986). Historical species-level diversity, or taxic, patterns (conceptualized as phylogenies) have long been considered a cornerstone of evolutionary theory (e.g., Alroy 2000; Gould 2002; McKinney 1990a; Fig. 7a). Phylogenetic patterns are the product of speciation and extinction dynamics and can be approached by causal analysis of rates of biological diversification. Since taxonomic ranks are arbitrary, the only meaningful approach to taxic diversity is through comparison of species-level diversity between sister groups (Cracraft 1984; Vrba 1980, 1984a). Taxic diversity patterns are typically studied by counting the distribution of taxa through time and typically represented by spindle diagrams (Gould et al. 1977, 1987; Raup et al. 1973; Stanley et al. 1981) or diversity curves (Newell 1952, 1967; Sepkoski 1978, 1993) and the shape of their profiles investigated for biological significance.

Fig. 7Hypothetical examples of evolutionary patters at different hierarchical levels. At the level of monophyletic taxa (a), sister clades showing different diversity and disparity patterns: clade a 1 displays a low rate of taxic evolution and stasis in disparity; clade a 2 exhibits a high turnover rate accompanied by a passive directional trend in disparity (a 3 ). At the species level, species lineage remains in stasis, showing minimal oscillations around a stable mean (b), whereas at the population level, component demes (c) continually differentiate, merge, or become extinct, producing short-lived diversity and disparity patterns of stability (c 1 , d 1 ), directional change (c 2 , d 2 ), divergence (c 3 , d 3 ), or decline (c 4 , d 4 ). Gray plane in c indicates an instantaneous cross section of the species lineage described by a corresponding disparity profile in d (inspired by Eldredge and Gould 1972: Fig. 5–10 and Miller 2006: Fig. 3)

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.