BIO 240 Week 3 Notes
BIO 240 Week 3 Notes BIO 240
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This 3 page Class Notes was uploaded by Miriam Valenzuela on Monday February 16, 2015. The Class Notes belongs to BIO 240 at San Francisco State University taught by Dr. Andrew Swei and Dr. Dennis Desjardin in Spring2015. Since its upload, it has received 39 views. For similar materials see Second Semester Biology in Biology at San Francisco State University.
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Date Created: 02/16/15
BIOLOGY 240WEEK 3 020915 Lecture 1 Species and Speciation Macroevolution the origin of taxonomic groups Speciation origination of diversity in higher taxa Species Concept dictated by available data Anagenesis adding up of changes which are associated with the transformation of one species into another Cladogenesis branching evolution budding of one or more new species from a parent species Species Kind or Appearance Morphological Species Biological Species Evolutionary Species Morphological Species focuses on the overall similarity of the organisms combination of anatomical and physiological features if individuals have similar morphologies they belong to the same species Problem does not address relatedness Biological Species Ernst Mayr introduced biological species to distinguish diversity Defined species Species population or group whose members can interbreed and receive viable fertile offspring Problem biological species doesn t extend to some plants who hybridize Problem Does not work for asexual organisms and fossils E volutionarv Species lndividuals who share a common ancestor Problem does not work for fossils Problem have to defined genetic variation and limit the way they categorize species What inhibits genetic exchange Reproductive Isolation Reproductive lsolation barriers that occur before mating and fertilization such as prezygotic barriers and postzygotic barriers Prezygotic Barriers doesn t allow mating between species which prevents fertilization of the ova if different species try to mate Habitat isolation behavioral isolationtemporal isolation mechanical isolation gametic isolation geographical isolation can be considered a prezygotic barrier Geographic lsolation two organisms that live in different geographic areas which are unlikely to meet and attempt mating Alopatric populations that occupy different geographic area Sympatric populations that occupy the same geographic area Habitat lsolation two organisms that exist in different habitats even in same geographic areas are not likely to meet and attempt mating Ex Garter snakes Thamnophis one type is aquatic and the other is terrastrial Behavioral lsolation elaborate behavior to attract mates Ex bird songs foot drumming nest building Temporal lsolation two species that breed during different times of the day year seasons Ex Nocturnal vs Diurnal Species Mechanical Isolation related species try to mate but are unable to because they don t have corresponding anatomies Ex chihuahua and great dane Gametic Isolation gametes of two species don t form a zygote because for one reason or another fusion doesn t occur Ex Environment is key gamete recognition relies on the release of specific molecules in the egg s coat without these there will be no fusion or fertlization Postzygotic Barrier prevent hybrid zygote from developing Hybrid offspring between two different species Reduced hybrid viability hybrid inviability incompatibility of species prevents the development of offspring for being frail and not able to survive Some hybrids are infertile they can t breed with either of the parental species Speciation how gene flow is interrupted Allopatric Speciation geographic separation Mountain ranges glaciers land bridges splintering of lakes colonization of a few individuals becoming isolated Small and isolated populations makes it easier to alter the gene pool organisms can be carried by other organisms to new habitats Sympatric Speciation biological factors chromosomal changes nonrandom mating crossing over reduce gene flow Adaptive Radiation evolution of adapted species with a common ancestor Ex Hawaiian Archipelago
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