Week of March 7
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This page Class Notes was uploaded by Katlyn Burkitt on Wednesday March 16, 2016. The Class Notes belongs to Biol 202 at Towson University taught by J. LaPolla in Spring 2016. Since its upload, it has received 20 views. For similar materials see Intro to Ecology and Evolution in Biology at Towson University.
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Date Created: 03/16/16
Biol Lecture 3716 31116 Domain Kingdom Phylum Class Order Family Genus Species Species concepts 0 Distinctiveness of species that occur together in a single locality 0 Connections that exist among different pioulations belonging to the same species Typological species concept 0 A group of organisms Where individuals are members of the species if they sufficiently conform to certain fixed properties Biological Species Concept 0 Species are populations that can potentially interbreed With one another and produce Viable fertile offspring o GeneticInterbreeding o EcologicalPopulation Variation is expected 0 MechanismReproductive isolation How do you assess species 0 Experiment Test cross 0 Field observations 0 Inference EX Sexual organs Isolating mechanisms 0 Prezygotic Isolating mechanism Prevents a zygote being created Ecological isolation Even if they may be able to produce offspring they are not in similar ecosystems therefore would not come into contact With each other Behavioral isolation Courtship rituals Sound behavior and pheromones only certain behavior Will allow organisms to mate Temporal isolation Species reproduce in different seasons or times Mechanical isolation Parts do not t Prevention of Gamate fusion Gametes of one population cannot fuse With the gamete of another 0 Postzygotic isolating mechanisms Prevents zygote from being viable Hybrid infertility or inviability 0 Problems I Interbreeding can be hard to determine I Hybrids I Asexual species Phylogenetic Species Concept A species is an evolving lineage 0 Features 0 Species are lineages 0 Species as historical entities I Species have an origin Process Cladogenesis I Lineages undergo evolution I Species go extinct o Difficulties o Requires a phylogeny O 221 Learning outcomes 0 Distinguish between the biological species concept and the ecological species concept 0 Define the two types of reproductive isolating mechanisms 0 Describe the relationship of reproductive isolating mechanisms to the biological species concept Sympatric Species 0 Inhabit the same locale but remain distinct o Phenotypically different and use different part of the habitat and behave differently Geographic Variation 0 Within a species organisms that occur in different areas may be distinct from one another 0 May be classified as subspecies or race 0 In areas Where the populations occur close together they may share characteristics of both populations Biological species concept and the ability to exchange genes Further Explained in Lecture 0 Gene pool All the alleles present in a species 0 Gene ow can maintain geographical distant populations to continue to be connected 0 Reproductive Isolation and its mechanisms Lecture Notes Ecological species concept 0 Will not cover in notes due to his purposeful exclusion in lecture 222 Learning outcomes 0 Define reinforcement in the context of reproductive isolation 0 Explain the possible outcomes When two populations that are partially reproductively isolated and become sympatric Selection may reinforce isolating mechanisms 0 Formation of species is a continuous process 0 Some populations that are ecologically or behaviorally isolated they still may be able to mate and reproduce and the Postzygotic barriers may be incomplete allowing for a viable offspring that may have a lower survival rate or reduced fertility 0 The concept that incomplete Postzygotic barriers are reinforced by natural selection until they are completely effective 0 Allopatric Geographically separated species 223 amp 224 Learning Outcomes 0 Describe the effects of genetic drift on a population 0 Explain how genetic drift and natural selection can lead to speciation How does speciation occur 1 Initially identical populations must diverge 2 Reproductive isolation must occur to maintain these differences 0 Sympatric speciation o Speciation Within the same location 0 Can occur instantaneously 39 Occurs When an individual is born that is reproductively isolated from all other members of its species I Through polyploidy 0 Individuals have more than two sets of chromosomes 0 Autopolyploidy o All chromosomes arise from a single species 0 EX When an error in cell division causes a doubling of chromosomes creating Tetraploids Organisms with four sets of chromosomes I Tetraploids can selffertilize or mate with other tetrapod s but cannot mate and produce fertile offspring with normal diploid organisms I This is because they produce diploid gametes that produce triploid offspring when combined with the haploid gametes from diploid organisms I Triploids are sterile because of the odd number of chromosomes 0 Allopolyploidy o More common 0 Occurs when two species hybridize I The resulting offspring is usually infertile due to have one copy of chromosomes from each species therefore they cannot match correctly I However these species can become fertile through several events including the error that causes tetraploidity may be able to reproduce asexually 0 Can also occur over the course of multiple generations I Disruptive selection 0 Can cause a population to contain individuals with two different phenotypes o This will only work if the two phenotypically different parties develop reproductively isolating mechanisms 225 Learning Outcomes 1 Describe adaptive radiation 2 List conditions that may lead to adaptive radiation 0 Adaptive radiation 0 The existence of groups of closely related organisms that recently diverged from a common ancestor but have adapted to different parts of the environment 0 Common in environments with few species but many resources I EX New islands formed through volcanic activity or catastrophic events leading to mass extinction 0 Can also occur when a new trait called a key innovation evolves within a species allowing it to use resources or other aspects of the environment that were previously inaccessible o Requires both speciation and adaptation to different habitats 0 Character displacement 0 Natural selection favors those individuals that use resources not used by other species so populations on different islands evolve to become different species causing the species to diverge o The finches were used as another example however since they are covered extensively in lecture as well as several other chapters I will not cover them here 0 There are several other examples of speciation in this chapter 226 Learning Outcomes 1 Define stasis and compare it to gradual evolutionary change 2 Explain the components of the punctuated equilibrium hypothesis Gradualism 0 The accumulation of small changes over several generations Punctuated equilibrium 0 Species experience periods of little to no change followed by periods of rapid evolutionary change
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