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In addition, pressure from natural selection is especially intense, as peripheral isolated populations exist at the outer edges of ecological tolerance. If most evolution happens in these rare instances of allopatric speciation then evidence of gradual evolution in the fossil record should be rare.
This phenomenon is shown in the forelimbs of mammals. For example: In monkeys, the forelimbs are much elongated, forming a grasping hand used for climbing and swinging among trees. Pigs have lost their first digit, while the second and fifth digits are reduced. The remaining two digits are longer and stouter than the rest and bear a hoof for ...
On the other hand, a species with a highly specialized ecological niche is more effective at competing with other organisms. [ citation needed ] For example, a fish and its parasites are in an evolutionary arms race , a form of coevolution , in which the fish constantly develops defenses against the parasite, while the parasite in turn evolves ...
Bergmann's rule - Penguins on the Earth (mass m, height h) [1] Bergmann's rule is an ecogeographical rule that states that, within a broadly distributed taxonomic clade, populations and species of larger size are found in colder environments, while populations and species of smaller size are found in warmer regions.
In an influential paper, Wiens and Donoghue [3] laid out how phylogenetic niche conservatism might help explain the latitudinal diversity gradient.While support for the hypothesis that niche conservatism drives latitudinally structured variation in species richness has been found in some clades, [11] overall, phylogenetic niche conservatism has not received strong support as the underlying ...
After immigration, birds, and some reptiles or mammals, tend to become larger and predatory, [6] showing relaxed intraspecific competition. [7] For mammals, small species will increase in size and large species will decrease in size. [8] This is referred to as the “island rule,” and is suggested to minimize energy expenditure. [9]
Dried examples of "neotropical anachronisms" from Brazil, Peru, and Nicaragua in the herbarium of the New York Botanical Garden. [1]Evolutionary anachronism, also known as "ecological anachronism", [1] is a term initially referring to attributes of native plant species (primarily fruit, but also thorns) that seemed best explained as having been favorably selected in the past due to their ...
Hyracodontidae developed long limbs and long necks that were most pronounced in the Paraceratherium (formerly known as Baluchitherium or Indricotherium), the second largest known land mammal ever to have lived (after Palaeoloxodon namadicus [30]). The rhinos (Rhinocerotidae) emerged in the Middle Eocene; five species survive to the present day.