PPT-Ch. 24 – The Origin of Species

What is a Species Speciation the origin of new species The biological species concept defines a species as a population or group of populations whose members have the potential to interbreed with one another in nature to produce viable fertile offspring but who cannot produce viable fertile offspring with members of other species. 19 Macroevolution is essentially the formation of new species (speciation) and accompanying events. . Reproductive isolation can occur in a variety of ways. Reproductive isolation is the key to cladogenic speciation. Cynotilapia. . afra. , introduced at West . Thumbi. Island in Lake Malawi in the 1960s, has split into two genetically distinct populations, located at the north and south ends of the island. How can scientists determine whether these populations are now different species, according to the biological species concept?. University of Technology . Invasive Species Research and Management Unit . AQUATIC (WATER). . INVASIVE SPECIES. IN ZIMBABWE. Water hyacinth (. Eichhornia. . crassipes. (. Martius. ) . Origin. : . Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. Part C. Allopatric. and Sympatric Speciation: . A Review. In . allopatric. speciation, geographic isolation restricts gene flow between populations. Reproductive isolation may then arise by natural selection, genetic drift, or sexual selection in the isolated populations. KEY CONCEPTS. • Although many species persist for long periods of time both genotypic and phenotypic changes occur over time.. • Even if change is occurring, individuals that interbreed within a population(s) maintain the status of the population(s) as a species.. Question?. What is a species?. Evolution . theory must also explain how species originate.. Darwin’s “Mystery of mysteries. ”. In the Galápagos Islands Darwin discovered plants and animals found nowhere else on Earth. “Both in space and time, we seem to be brought somewhat near to that great fact—that mystery of mysteries—the first appearance of new beings on this Earth.”. — Darwin. What is a species?. Biological species concept. Cartoon – gentleman and ape. 2. Key Concepts:. Species concepts. Development of reproductive isolation. Patterns of speciation. Macroevolution. Human evolution. Evolution continues…... 3. specie. Macroevolution. describes the origination of new taxonomic groups (vs . microevolution. , which deals with change in allele frequency, and frequencies of genotype and phenotype). What is a species?. Species. Part B. How do species occur?. Concept . 24.2: Speciation can take place with or without geographic separation. Speciation can occur in two ways:. Allopatric. speciation. Sympatric . speciation. Reduction in . gene . flow, genetic and phenotypic change in populations. The study of speciation requires that species be real. Speciation. Speciation is the antidote to sex. Keeps together adaptive groups of traits. Campbell . and Reece. Speciation. process by which one species splits into 2 or more species. Speciation explains both the diversity of life and the unity of living things.. Speciation : forms bridge between:.