Exam 1 Flashcards
Allopatric Speciation
Greek word: allo- other, patra-homeland
gene flow is interrupted when a population is divided into geographical isolated subpopulations
Aristotle
Greek philosopher who viewed species as fixed and unchanging. created the ‘scala Naturae’ and concluded that life-forms could be arranged on a ladder of increasing complexity.
sympatric speciation
speciation occurs in populations that live in the same geographic area. Caused by polyploidy, habitat differentiation, and sexual selection.
speciation
The process by which one species splits into two or more species.
microevolution
mechanisms such as mutations, natural selection, genetic drift, and gene flow.
macroevolution
origin of new groups or organisms such as mammals or flowering plants through a series of speciation events.
sexual selection
females select males based on their appearance.
species
a group of populations whose members have the potential to interbreed in natureand produce viable, fertile offspring but do not produce viable fertile offspring with members of other such groups.
gene flow
The transfer of alleles into or out of a population due to the movement of fertile individuals or their gametes.
prezygotic barriers
- impeding members of different species from attempting to mate 2. by preventing an attempted mating from being completed successfully 3. by hindering fertilization if mating is completed successfully.
habitat isolation, temporal isolation, behavioral isolation, gametic isolation and mechanical isolation
Habitat Isolation
type of prezygotic barrier. Two species that occupy different habitats within the same area may encounter each other rarely, if at all, even though they are not isolated by obvious physical barriers, such as mountains.
ex: Thamnophis snake
Temporal isolation
Type of prezygotic barrier. Species that breed during different times during the day, different seasons, or different years cannot mix their gametes. ex: western and eastern snake.
Behavioral Isolation
type of prezygotic barrier. Courtship rituals that attract mates and other behaviors unique to a species are effective reproductive barriers, even between closely related species. Such behavioral rituals enable mate recognition- a way to identify potential mates of the same species. ex: Blue-footed boobies
Mechanical Isolation
type of prezygotic barrier. Mating is attempted, but morphological differences prevent its successful completion. ex. two species of snails.
Gametic Isolation
Type of prezygotic barrier. Sperm of one species may not be able to fertilize the eggs of another species.Sea Urchins.
Postzygotic barrier
reproductive isolation after the hybrid zygote is formed. 1. Developmental errors may reduce survival among hybrid embryos 2. hybrids can be infertile.
Reduced Hybrid viability
The genes of different parent species may interact in ways that impair the hybrid’s development or survival in its environment. ex. salamander hybrids
Reduced Hybrid Fertility
Postzygotic barrier. The chromosomes of the two parent species differ in number or structure, meiosis in the hybrids may fail to produce normal gametes. ex mule
Hybrid breakdown
Postzygotic barrier. Some first generation hybrids are viable and fertile, but when they mate with one another or with either parent species, offspring of the next generation are feeble or sterile. ex:strains of rice.
Evolution
Descent with modification. A change in the genetic composition of a population from generation to generation
Uniformitarianism
Proposed by Charles Lyell, idea that the same geological processes are operating today as in the past.
J. Lamarck
proposed a mechanism for how life changes. the “use and disuse” idea. The idea that body parts that are used extensively become larger and stronger and those that are not deteriorate. Also, “inheritance of acquired characteristics” giraffes got their long necks over many generations of stretching their necks ever higher.
Carlo Linnaeus
created the binomial naming of species and grouped similar species into increasingly general categories based on their pattern of creation.
Charles Darwin
Coined the ‘decent with modification’ about evolution. Traveled on the Beagle to South America where he studied plants and animals. He noticed an important detail about the Finches in the Galapagos Islands which led to his theory of Natural Selection. Published book “On the Origin of Species by Means of Natural Selection
Natural Selection
a process in which individuals that have certain inherited traits tend to survive and reproduce higher rates than other individuals because of those traits.
Charles Lyell
proposed the uniformitarianism theory