BIOL 102 Study Guide - Midterm Guide: Sympatric Speciation, Allopatric Speciation, Hibiscus Rosa-Sinensis
The Origin of Species or Speciation
● Microevolution
o Changes in allele frequency from generation to generation within a population of a
species
● Speciation
o Process in which one species splits into two or more species
● Macroevolution
o Evolutionary changes above species level
o Origin of evolutionary novelty
o Gain and loss of taxonomic groups
What is a Species?
● Species is a Latin word meaning
o kid
o appearae
● The biological species concept defines a species as
o Group of populatios—members have potential to interbreed nature to produce fertile
offsprig.
Species Concepts
● Biological species
o Reproductively isolated
o Sexually reproducing eukaryotes
o Cannot be applied to all organisms ( not applicable to asexually reproduced creatures)
Other species concepts
● Morphological: based on measureable physical traits
o Non-sexual species (prokaryotes)
o Extinct species(fossils)
● Molecular
o Gene and protein sequences
Wh do’t eers of differet speies iterreed?
● Reproductive barrier: prevents successful interbreeding b/t different species
● What is a zygote?
o Sperm and egg gamete combines and fertilizes
● Prezygotic barriers prevents mating or fertilization b/t species
● Postzygotic barriers operate if interspecies mating take place producing hybrid zygotes
o Hybrid in a new context
Look at figure 14.3
Mechanical isolation: physically cannot mate
Gametic isolation: sea urchin species whose gametes cannot fuse
What are the Mechanism of Speciation?
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● Parent population splinters—which form of allele frequency change is prevented?
● Two mechanisms of splitting
o Allopatri speiatio differet outr
o Geographic isolation
● “patri speiatio sae outr
o Cell division accident
o Extra set of chromosomes
▪ Polyploidy
How does allopatric speciation take place?
● Reproductive barriers develop b/t the two pops
o How does this happen? How do population change?
o Genetic drift, natural selection, adaptation
● If the two populations come back into contact
o Reproductive barriers prevent interbreeding
o Maintain separate species
o Hoeer…….
Sympatric speciation—hybridization followed by chromosome doubling
How is sympatric speciation different from allopatric speciation?
● Sympatric speciation take place in one geographic area
● Accident of cell division—polyploidy
● Very common in plants
o Oats, potatoes, bananas, peanuts, coffee, wheat, Chinese hibiscus
● Less common in animals
o Some fish and amphibian species
Geologic time scale
● Paleozoic era: began 542 million years ago
● Mesozoic era: began 251 million years ago
o Pangea forms
o Mass extinction of marine species
o Pangea splits (135 million years ago)
● Cenozoic era: began 65 million years ago
o Meteor hit
o Extinction of non-avian dinosaurs
o Diversification of mammals and birds
Evolution of biological novelty
● What accounts for the dramatic differences b/t dissimilar groups?
o Turtle shells
o Wings and flight
o Flowers
o Eye
o Hearts
o Bipedalism
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Evolutionary novelty: What is an exaptation?
● Exaptation
o Structure that evolves in one context but becomes adapted for another function
o Evolutionary remodeling
o Gives rise to novel structures
Exaptation example: wings and flight in birds
● Bird wings= modified forelimbs previously adapted for non-flight functions
o Thermal regulation
o Courtship displays
o Camouflage
● The first flights=only glides or extended hops
● Pursue pretty or avoid predator
Diversity of Life
● Phylogeny
o Evolutionary history
o Infer past events with clues from the present
● Classification now
o Must reflect phylogeny
o Branch points
▪ Divergence of two lines from ancestral groups
Phylogenetic hypotheses
● Homologous characters-derived from common ancestry
o Fundamental similarities
o May vary in form and function
▪ Vertebrate forelimbs
● Beware of analogous characters
● Similarity not due to common ancestry
● Convergent evolution
● Wings of birds and insects
Introduction to Ecology
● Study of distribution of organisms and their interactions with the environment
o Biosphere: global processes
o Ecosystem: energy flux and cycling of nutrients
o Community: interactions among populations
o Populations: population dynamics; the unit of evolution
o Organism: survival and reproduction; the unit of natural selection
How is ecology related to evolution?
● Genetics
● Adaptations: physiology, behavior, anatomy
● Ecology: current interactions between organisms and environment, abundance and distribution
of organisms
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Document Summary
Microevolution: changes in allele frequency from generation to generation within a population of a species. Speciation: process in which one species splits into two or more species. Macroevolution: evolutionary changes above species level, origin of evolutionary novelty, gain and loss of taxonomic groups. Species is a latin word meaning: (cid:862)ki(cid:374)d(cid:863, (cid:862)appeara(cid:374)(cid:272)e(cid:863) offspri(cid:374)g. (cid:863) The biological species concept defines a species as: (cid:862)group of populatio(cid:374)s members have potential to interbreed nature to produce fertile. Biological species: reproductively isolated, sexually reproducing eukaryotes, cannot be applied to all organisms ( not applicable to asexually reproduced creatures) Morphological: based on measureable physical traits: non-sexual species (prokaryotes, extinct species(fossils) Reproductive barrier: prevents successful interbreeding b/t different species. What is a zygote: sperm and egg gamete combines and fertilizes. Prezygotic barriers prevents mating or fertilization b/t species. Postzygotic barriers operate if interspecies mating take place producing hybrid zygotes: hybrid in a new context. Gametic isolation: sea urchin species whose gametes cannot fuse.
