University:
University of Iowa
Course:
BIOL 14120AAA | Diversity of Form and Function
Academic year:

2022
Views:

380

Pages:

2
Author:

Kristopher Elliott

Species: groups of organisms that share a suite of genetic and morphological a reproductively isolated from other such groups - The base unit of taxonomic classification Speciation: the divergence of biological lineages and the emergence of reprodu between lineages Species concepts: ways that biologists think about existence of species We can recognize many species by their appearance Morphological species concept: the definition of a species as a group of indivi • This is useful but there are limitations because members of the same speci alike Cryptic species: species that are morphologically indistinguishable but do not in Biologists cannot rely on appearance alone in determining whether individual org members of the same or different species • Today, biologists use other information such as behavioral and genetic data species Reproductive isolation is a key feature in most species concepts Reproductive isolation: condition in which two divergent populations are no lon genes. Can lead to speciation Biological species concept: "Species are groups of actually or potentially inter populations which are reproductively isolated from other such groups." • "actually" -- says that the individuals live in the same area and interbreed w • "Potentially" -- says that even though the individuals do not live in the same interbreed, other information suggests that they would if they were able to g This does not apply to organisms that reproduce asexually and is limited to a sin • "actually" -- says that the individuals live in the same area and interbreed with one another • "Potentially" -- says that even though the individuals do not live in the same area, and don't interbreed, other information suggests that they would if they were able to get together This does not apply to organisms that reproduce asexually and is limited to a single point in evolutionary time The lineage approach to understanding species takes a long-term view Lineage species concept: the definition of a species as a branch on the tree of life, which has a history that starts at a speciation event and ends either at extinction or at another speciation event Lineage: a series of populations, species, or genes descended from a single ancestor over evolutionary time Each species has a history that starts with a speciation event (at which one lineage on the tree splits into two) and ends either at extinction or at another speciation event (at which the species produces two daughter species). The different species concepts are not mutually exclusive Morphological species concept emphasizes the practical aspects of recognizing species visually, although it sometimes results in underestimation or overestimation of the actual number of species Biological species concept emphasizes that reproductive isolation is what allows sexual species to evolve independently of one another Lineage species concept emphasizes that idea that sexual species are maintained by reproductive isolation, but extends the concept of a species as a lineage over evolutionary time The species-as-lineage concept also accommodates species that reproduce asexually Significant reproductive isolation between species is necessary for lineages to remain distinct over evolutionary time