Evolution and Species Biological Species PDF

Evolution and Species Announcements Tuesday 2/27 Homework 10 Thursday 2/29 No homework Exam 2 is Thursday 2/14 Learning Objectives Define evolution and compare it to the process of speciation Define, compare, and contrast microevolution and macroevolution Identify four species concepts (Morphologica...

Evolution and Species Announcements Tuesday 2/27 Homework 10 Thursday 2/29 No homework Exam 2 is Thursday 2/14 Learning Objectives Define evolution and compare it to the process of speciation Define, compare, and contrast microevolution and macroevolution Identify four species concepts (Morphological, Biological, Phylogenetic, and Ecological), explain the strengths and weaknesses of each, and describe types of organisms that each is best suited to Explain the concepts of morphology, morphotype, and cryptic species Explain what reproductive isolation is how it is related to species concepts Explain the process of divergent evolution, including the concepts of speciation and common ancestors Explain how traits change during divergent evolution (ancestral traits, derived traits, fitness advantage) Explain how complex traits may evolve through many steps and how traits can change over long periods of time Explain what convergent evolution is and how it impacts traits Evolution Evolution is genetic changes in a population over time (generations) Evolution occurs over single generations and can lead to speciation over long-periods of time in some cases. Evolution can lead to speciation Speciation: formation of a new species of organism For speciation to occur: - Evolution must happen over long time periods - A population must become genetically distinct from other populations Evolution has different effects depending on the timescale Microevolution: - changes in allele frequencies in a population over short periods of time (as short as one generational change). - Impacts traits, but does not lead to speciation Evolution has different effects depending on the timescale Macroevolution: - Many genetic changes over very long spans of time (hundreds of thousands or millions of years) in multiple populations - Impacts many traits and involves formation and extinction of species ID Different Species! Determine if the two organisms found are the same or different species Same (A) or different (B) species? Baleanoptera musculus Tursiops truncatus Morphological Species Concept Species: The idea that members of the same species look like each other more than like other species. Morphology: the form of living organisms and the relationship between their structures and functions. Same (A) or different (B) species? Canis domesticus Canis domesticus Traits Can Vary Within a Single Species Morphotype: a group of individuals of the same species with s specific set of physical traits Some organisms display very distinct morphotypes but are genetically the same species Same (A) or different (B) species? Eviota sebreei Eviota punyit Cryptic Species Cryptic Species: Species that traditionally were considered to belong to a single species because they look similar, but belong to two species because of differences at the DNA sequence level Biological Species Concept Species: a group of organisms that can reproduce with each other but are reproductively isolation from other organisms. Reproductive isolation occurs when individuals from two different populations cannot produce viable, fertile offspring Same (A) or different (B) species? Escherichia coli Pseudomonas aeruginosa Phylogenetic Species Concept Species: The idea that members of a species all share a common ancestry and a common fate DNA sequencing and molecular evolutionary principles are used to identify closely related groups of organisms Ecological Species Concept Species: The concept that there is a oneto-one correspondence between a species and its niche London Underground Mosquitos Do you think the underground and above ground mosquitos are the same species (A) or different species (B) London Underground Mosquitos Do you think the underground and above ground mosquitos are the same species (A) or different species (B) What information would help you answer this question more accurately? What information would help you answer this question more accurately? https://www.youtube.com/watch?v=GZgbwHFd_gc London Underground Mosquitos Based on this information, do you think they are the same species? Which species concept we apply to these mosquitos based on this information? A) Morphological B) Ecological C) Phylogenetic D) Biological Biological Species Concept Species: a group of organisms that can reproduce with each other but are reproductively isolation from other organisms. Reproductive isolation occurs when individuals from two different populations cannot produce viable, fertile offspring Reproductive Isolation can be Geological Geographical features physically separate populations Physical separation can lead to allopatric speciation in which new species arise in different locations Ecological Isolation can Physically Separate Species Two or more populations are evolutionarily adapted to live and survive in separate habitats, which keeps them separated Reproductive Barriers can be Biological New mutations in a population isolate limit reproduction between members of the same species Biological barriers can lead to sympatric speciation in which two new species arise in the same location How would you test for reproductive isolation between two putative species? Try to come up with multiple options and take into account practical limitations of working with animals in captivity Gene Flow Counteracts Reproductive Isolation Gene flow is the movement of alleles and genetic variation between populations Gene flow that occurs on a regular basis indicates that two populations are not reproductively isolated C. pipiens and C. molestus produce hybrid offspring Despite being able to hybridize, C. pipiens and C. molestus maintain distinct populations Do you think reproductive barriers are in place between these mosquito populations? Live above ground Feed on Birds Hibernate during cold seasons Breed in large swarms Require a blood meal to lay eggs Live below ground Feed on Rats/Humans Active all year Breed in pairs Do not require a blood meal Hybrids are viable, but two types of mosquitos are maintained Do you think C. pipiens and C. molestus mosquito could be defined as different species based on the biological species concept? C. pipiens and C. molestus mosquito are undergoing the process of speciation. Do you think gene flow is occurring between C. pipiens and C. molestus populations? A) Yes B) No Genetic Analysis of C. pipiens mosquitos Do you think gene flow is occurring between these two mosquito populations? Low level of gene flow between populations of C. molestus and C. pipiens Genetic Analysis of C. pipiens mosquitos C. molestus and C. pipiens are genetically distinct groups Which species concept we apply to these mosquitos based on this information? A) Morphological B) Ecological C) Phylogenetic D) Biological Where did C. molestus mosquitos come from? C. pipiens C. molestus Initial Hypothesis: C. molestus evolved from C. pipiens populations Where did C. molestus mosquitos come from? Initial Hypothesis: C. molestus evolved from C. pipiens populations Where did C. molestus mosquitos come from? New Hypothesis Based on genetic data: C. molestus evolved in Egypt and dispersed from there New Species Diverge from a Common Ancestor Speciation occurs through the process of divergent evolution Divergent Evolution: the process by which one interbreeding species splits into two or more separate evolutionary lineages New species arise from ancestral species called common ancestors A single species can evolve into another species or split and give rise to multiple new species Common ancestors: species that are a direct ancestor of two or more species Extant Species A Ancestral Species (Extinct) Species X Species Y Species Z Speciation Event Speciation Speciation Event Event Time Extant Species B T. Rex and Chickens – Evolutionary Cousins? This image shows the evolutionary history of two species, Domestic chickens and Tyrannosaurus rex Gansus yumenensis Aurornis xui Austinornis lentus Phasianid Gallus gallus Tyrannoraptoran Domestic chicken Proceratosaurus Eotyrannus lengi Daspletosarus torosus Tyrannosaurus rex All of the arrows in this diagram represent D. Homology E. Common Ancestors A. Divergence B. Speciation C. Convergence Gansus yumenensis Aurornis xui Austinornis lentus Phasianid Gallus gallus Tyrannoraptoran Domestic chicken Proceratosaurus Eotyrannus lengi Daspletosarus torosus Tyrannosaurus rex Which of the following is a common ancestor of T. Rex and Chickens A. Aurornis xui B. Gallus gallus C. Daspletosarus torosus D. Tyrannoraptoran E. Phasianid Gansus yumenensis Aurornis xui Austinornis lentus Phasianid Gallus gallus Tyrannoraptoran Domestic chicken Proceratosaurus Eotyrannus lengi Daspletosarus torosus Tyrannosaurus rex Traits change during Divergent Evolution Ancestral traits: Trait found in a common ancestors Derived traits: Traits found in descendants that evolved from an ancestral form Tyrannoraptoran Small Feathered Bipedal Long, Three-fingered forlimbs Carnivores Tyrannosaurus rex Large Feathered (?) Bipedal Short, Two-fingered forlimbs Carnivores Domestic Chicken Small Feathered Bipedal Forlimbs are wings Omnivores Changing traits help organisms adapt to their environment Evolution favors traits that give organisms an advantage in terms of survival and reproduction are in their environment Environments change, and traits change along with them https://www.youtube.com/watch?v=5Ier8c9WFzE Traits can be lost and gained in divergent evolution The legs of early tetrapods evolved from the fins of Lobe-finned fish Millions of years later, the flippers of whales evolved from the legs of land-dwelling mammals Complex Traits can arise through many steps Each intermediate trait provides an advantage to the organism that possesses it Similar Traits can Arise Through Convergent Evolution Flight has evolved three separate times in mammals All groups share the ancestral bone structure of early tetrapods but have very different derived wing anatomy Similar Traits can Arise Through Convergent Evolution Eight types of eyes in animals The ability to detect shape and light are highly advantageous Many different eye structures have evolved in the animal kingdom What use is Half A Wing – iClicker Question At first glance, it seems unlikely that intermediate wings would evolve because: A. Intermediate wings have structures unrelated to other limb structures in animals B. Wing structures are too complicated to evolve in multiple steps C. Intermediate wings cannot provide the advantage of flight D. Intermediate wings were energetically expensive to produce E. Intermediate wings are analogous to modern wings What use is Half A Wing – iClicker Question Fledglings for many different extant bird species use their partially formed wings to assist in climbing. Based on this information, this trait: A. Likely arose through convergent evolution B. Likely arose through divergent evolution C. Was present in the common ancestor of modern birds D. Is an exaptation E. Is a derived trait What use is Half A Wing – iClicker Question Feathers may have originally evolved for purposes of insulation or mate attraction and later been coopted by evolution for flight. Based on this, the use of feathers for flight is an example of an: A. Ancestral trait B. Convergent evolution C. Derived trait D. Exaptation E. Common ancestor