SCIN130 Chapter 16 exam questions fully solved & updated

Macroevolution changes in a population over very long periods of time. Speciation the splitting of one species into two or more new species Biological Species Concept offers testable way to define a species that does not depend on appearance: The members of a species interbreed and have a shared gene pool, & each species is reproductively isolated from every other species. Gene flow occurs between the populations of a species, but not between pops of diff species. Biological species concept limitations applies only to sexually reproducing organisms and cannot apply to asexually reproducing organisms. Common Ancestor a single ancestor for two or more different groups. Reproductive Barriers isolating mechanisms that prevent successful reproduction Prezygotic Isolating Mechanisms occur before the formation of a zygote. Prevent reproductive attempts and make it unlikely that fertilization will be successful. Habitat isolation, temporal isolation, behavioral isolation, mechanical isolation, and gamete isolation. Habitat Isolation When 2 species occupy different habitats, even within the same geographic range. Temporal Isolation 2 Species can live in the same locale, but they reproduce at different times of the year. Behavioral Isolation Many animals have courtship patterns that allow males and females to recognize one another. Ex: sight, sound, chemicals, pheromones Mechanical Isolation When animal genitalia or plant floral structures are incompatible. Gamete Isolation Even if the gametes of 2 different species meet, they may not fuse to become a zygote. In animals, sperm may not survive reproductive tract, or egg may only accept sperm of its species. Postzygotic Isolating Mechanism occur after the formation of a zygote. Prevent hybrid offspring from developing or breeding, even if reproductive attempts have been successful. Zygote mortality or hybrid sterility. Zygote Mortality The hybrid zygote may not be viable, so it dies. May fail to go through mitosis properly, or embryo receives incompatible instructions Hybrid Sterility Hybrid zygote may develop into a sterile adult. Generally results from complications in meiosis F2 Fitness If hybrids can reproduce, their offspring are unable to reproduce. Allopatric Speciation A speciation model based on geographic isolation of populations Sympatric Speciation population develops into 2 or more reproductively isolated groups without prior geographic isolation. Example: plants through polyploidy, an increase in # of sets of chromosomes to 3n or above. Adaptive Radiation Many new species evolve from a single ancestral species. Seen in Darwin's finches. Fossils traces and remains of past life or any other direct evidence of past life. Paleontology the science of discovering and studying the fossil record and, from it, making decision about the history of species. Geological Timescale divides the history of life on Earth into eras, periods, then epochs. Includes descriptions of the types of fossils common to each of these divisions of time. Oldest to Youngest: Precambrian Paleozoic Mesozoic Cenozoic Cenozoic era only era where periods are divided into epochs. More attention is given to the evolution of primates and flowering plants than earlier evolving organisms. Paleozoic After Precambrian Era (beginning of Earth). "Age of Ancient Life". Humans have been around about .04% of the history of life Prokaryotes existed for some 2 billion years before the eukaryotic cell and multicellularity arose during Precambrian time. Some prokaryotes became the first photosynthesizers to add oxygen to the atmosphere.