Speciation and its type
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Speciation is the process by which new biological species develop. It occurs through reproductive isolation, which can develop due to geographic barriers separating populations or behavioral/ecological factors preventing interbreeding. There are several types of speciation including allopatric, where populations are isolated geographically; parapatric, involving isolation in adjacent habitats; and sympatric, occurring without geographic separation through mechanisms like habitat differentiation. Reproductive barriers that maintain species include prezygotic barriers preventing fertilization and postzygotic barriers hindering viable offspring.
Speciation and its type
- 2. • Can be caused by a change in just 1 gene or a set of genes causing some sort of isolation Speciation • Development of a new species through a variety of factors • Rate of speciation depends on generation time, environmental conditions, etc.
- 3. Biological Species Concept Species-Group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring, but do not produce viable offspring with members of other groups. What maintains species? Gene flow Reproductive isolation (biological)
- 4. Smallest group of organisms that share a common ancestor Other Species Definitions Morphological Species Concept Characterizes by body shape and other structures Ecological Species Concept Characterizes in terms of ecological niche Phylogenetic Species Concept
- 5. • block fertilization from happening • Prevent different species from attempting to mate • Prevent an attempted mating from being successful • Hindering fertilization Prezygotic Barriers- Postzygotic Barriers • occur after zygote is formed • Developmental errors • Birth defects cause death • Infertile offspring
- 6. Behavioral isolation- Absence of cross-attraction between individuals of separate species inhibiting any courtship initiation or individual behavior during copulation does not allow normal fertilization to occur. Ecological isolation-Variations in the ecology of species give rise to barriers: Habitat isolation-Even when living in the same common locality, species occupy diverse habitats due to different biological or genetic tendencies thereby limiting gene flow during breeding seasons. Temporal isolation-Species living in the same area have different breeding seasons preventing gene flow. Pollinator isolation-Flowering plants have varying interactions with pollinators thereby reducing gene flow. Mechanical isolation-Reproductive structures are incompatible between species inhibiting copulation or pollination. Gametic isolation-Gametes that are transferred during copulation or pollination are ineffectual for fertilization due to problems with storage or transfer of gametes or because of conspecific pollen or sperm partiality. Prezygotic Reproductive Isolating Barriers
- 7. Types of Speciation Sympatric Speciation--occurs in populations that live in the same geographic area • Less common than allopatric speciation • Happens when gene flow is diminished by: • Polyploidy Habitat differentiation Sexual selection Allopatric Speciation-gene flow is interrupted when a population is divided into geographically isolated subpopulations Parapatric Speciation-occurs when part of a population enters a new habitat bordering the range of the parent species Some gene flow may occur between populations in border zone
- 8. Allopatric Peripatric Parapatric Sympatric Initiation of speciation Evolution of reproductive isolation New distinct species after equilibration of new ranges Barrier formation In isolation New niche entered In isolation niche New niche entered In adjacent niche Genetic polymorphism With population