Q1:what are the two major reproductive barriers?
A1:prezygotic and post zygotic.
Q2: what's speciation?
A2:the process by which one species splits into two or more species.
Q3: what are the major speciation?
A3: allopatric speciation and sympatric speciation
Five Facts:
1. the biological species concept emphasizes reproductive isolation
2. speication can take place with or without geographic separation
3. hybrid zones provide opportunities to study factors that cause reproductive isolation
4. speciation can occur rapidly or slowly and can result from changes in few or many genes
5. speciation is the process by which one species splits into two or more species.
Figure:
in a punctuated pattern, new species change most as they branch from a parent species and then change little for the rest of their existence. Other species diverge from one another much more gradually over time.
Summary:
Speciation is the process by which one species splits into two or more species. As biological species concept, a species is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring- but do not produce viable, fertile offspring with members of other such groups. Reproductive isolation is the barriera that impede members of two species from producing viable, fertile offspring. It includes prezygotis barriers and postzygotic barriers. Prezygotic blocks fertilization from occuring, which contains habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gametic isolation. Postzygotic contribute to reproductive isolation after the hybrid zygote is formed. It reduces hybrid viability, hybrid fertility,and hybrid breakdown. Morphologica species concept characterizes species by body shape and other structural features. Eological species concept views a species in terms of its ecological niche, the sum of how members of the species interact with the nonliving nad living parts of their environment. Phylogenetic species concept defines a species as the smallest group of individuals that share a common ancestor, forming one branch on the tree of life.
Allopatric speciation, gene flow is interrupted when a population is divided into geographically isolated subpopulations. Reproductive isolation between teo populations generally increases as the distance between hem increases. In sympatric speciation, speciation occurs in population that live in the same geographic area. An autopolyploid is an individual that has more than two chromosome sets that are all derived from a single species. Allopolyploid is the mehcanism can change a sterile hybrid into a fertile polyploid. Hybrid zone is a region in which members of different species meet and mate, producing at least some offspring of mixed ancestry. Reinforcement: hyvrids gradually cease to be formed. Fusion: the two species fuse. Stability: continued production of hybrid individuals.
Video:
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