Bio102 22GSW

BIO 102 General Biology II Name Desirae Porter Guided Study Worksheet Chapter 22 Define the following terms: Speciation the process by which one species splits into two or more species. Microevolution changes over time in allele frequencies in a population Macroevolution the broad pattern of evolution above the species level. What is the biological species concept? Definition of a species as 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. What is the meaning of reproduction isolation? The existence of bio- logical factors (barriers) that impede members of two species from producing viable, fertile offspring. What is a zygote? The diploid cell produced by the union of haploid gametes during fertilization; a fertilized egg. Explain the difference between prezygotic and postzygotic barriers to reproduction? Prezygotic: prevent mating or fertilization between different species, preventing the successful completion of mating and hindering fertilization if mating is successful. Postzygotic: prevent the hybrid zygote from developing into a viable, fertile adult Identify each of the following as prezygotic or postzygotic barriers and write a description of each: Habitat isolation Two species encounter each other rarely, or not at all, because they occupy different habitats, even though not isolated by physical barriers (snakes) Temporal isolation Species that breed at different times of the day, different seasons, or different years cannot mix their gametes (skunks) Behavioral isolation Courtship rituals and other behaviors unique to a species are effective barriers (blue footed boobies) Mechanical isolation Morphological differences can prevent successful mating (snails) Gametic isolation Sperm of one species may not be able to fertilize eggs of another species (sea urchins) Reduced hybrid viability refers to a lower potential to survive for organisms whose parents have incompatible genetics, mostly because these parents mated despite being different species Reduced hybrid fertility is when the offspring is healthy but usually sterile. Hybrid breakdown is a type of reproductive failure that appears after the F2 generation of crosses between different species or subspecies. Detail these definitions of species: Morphological species concept The concept defines a species by structural features. It applies to sexual and asexual species but relies on subjective criteria. Paleontological species concept Ecological species concept The concept views a species in terms of its ecological niche. It applies to sexual and asexual species and emphasizes the role of disruptive selection Phylogenetic species concept The concept defines a species as the smallest group of individuals on a phylogenetic tree. It applies to sexual and asexual species, but it can be difficult to determine the degree of difference required for separate species What is the basis for allopatric speciation? State evidence that this occurs. A gene flow is interrupted when a population is divided into geographically isolated subpopulations. For example, the water level in a lake may subside, resulting in two or more smaller lakes that are now home to separated populations What does sympatric speciation mean? Give examples of when this occurs. Speciation occurs in populations that live in the same geographic area.It occurs when populations of a species that share the same habitat become reproductively isolated from each other. What is the difference between autopolyploidy and allopolyploidy? Autopolyploidy appears when an individual has more than two sets of chromosomes, both of which from the same parental species. Allopolyploidy, on the other hand, occurs when the individual has more than two copies but these copies, come from different species. In what type of organisms is polyploidy speciation more common? why do you think this occurs? Polyploidy speciation is more common in plants because they reproduce much differently than animals. What is adaptive radiation? how do island chains relate to this topic? It is the emergence of species from a common ancestor introduced to a new environment with new diversity. It is discussed with islands because many species recolonize on neighboring islands that have different environments. Compare and contrast the models of punctuated equilibrium to gradualism as models for the rate of evolution. Does one have to exclude the other? Punctuated equilibrium shows large changes in a species in a short amount of time, while gradualism, as the name suggests, shows slower, gradual changes. Normally, punctuated equilibrium excludes gradualism. Discuss three possible outcomes that may occur in a hybrid zone over time. First strengthening of reproductive barriers. Second weakening of reproductive barriers Third continued formation of hybrid individuals Define the following terms: Heterochrony Evolutionary change in the timing or rate of an organism’s development. Allometric growth Paedomorphosis The retention in an adult organism of the juvenile features of its evolutionary ancestors. Homeotic genes Any of the master regulatory genes that control placement and spatial organization of body parts in animals, plants, and fungi by controlling the developmental fate of groups of cells. What impact have the Hox genes had on vertebrates? They have introduced positional information to animal embryos. How does the evolution of the horse exemplify the concept that evolution is driven by the interactions of the organism and its environment?