BSC2010-evolution-9-2023 - Tagged.pdf

Macroevolution II: Speciation and Extinction BSC2010, Fall 2023 Summer Research? National Science Foundation Research Experience for Undergraduates (i.e., NSF REU) https://www.nsf.gov/crssprgm/reu/ Lecture Schedule Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Oct 27...

Macroevolution II: Speciation and Extinction BSC2010, Fall 2023 Summer Research? National Science Foundation Research Experience for Undergraduates (i.e., NSF REU) https://www.nsf.gov/crssprgm/reu/ Lecture Schedule Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Fri Mon Wed Oct 27 Oct 30 Nov 1 Nov 3 Nov 6 Nov 8 Nov 10 Nov 13 Nov 15 Nov 17 Nov 20 Nov 22 Nov 24 Nov 27 Nov 29 Dec 1 Dec 4 Dec 6 Introduction to Evolution Natural Selection Exam 2 Review Sexual Selection Processes of Evolution I Processes of Evolution II Veteran’s Day: No Class Genome Evolution Phylogenetics 1 Phylogenetics 2 Macroevolution 1: Origin of Species Thanksgiving - no class Thanksgiving - no class Macroevolution 2: Speciation and Extinction Human Evolution Origins and Early Diversity of Life TBA, and Exam 3 No Class 13 13 13 13 15 14 14 16 16 22.7, TBA 17, 19.0-19.2 …..Recall Evolution: Descent with modification Natural selection: Differential reproductive success Outline • What is the tempo of speciation/evolution? • gradual vs. punctuated • What is the tempo of extinction? How does it relate to speciation? • What are the factors that govern rates of speciation and extinction? The tempo of speciation • Classic, gradualistic model: slow divergence of isolated populations • Punctuated equilibrium: long periods of stasis followed by sudden episodes of speciation • Earths history shows periods of slow evolution punctuated by periods of rapid evolution • Cichlid fishes in Lake Victoria: 400 species in 12,000 years • Horseshoe crabs: Phenotypic stasis for 100,000,000 years gradual vs. punctuated change What controls the rate of speciation? • rates of mutation • rates of selection • competition among species • available habitat • generation time • rates of environmental change This combination of factors drives the rate of innovation! But remember…natural selection can only act on structures currently in place for another use Specific changes leading to rapid speciation • Key genetic processes change phenotype, but maintain function • polyploidy • Key developmental processes change phenotype, but maintain function • Alteration of genes that control organism structure • mutations in hox genes • Heterochrony: changes in developmental timing or sequence Heterochrony: Two Types • Sequence heterochrony: Change in the time of appearance of a structure • Allometric heterochrony: Change in the rate of development/growth. Allometric Heterochrony Sequence Heterochrony Axolotl and Neoteny Sequence Heterochrony and Neoteny in Humans? Rates of Extinction • continuous process, always occurring at some background rate due to chance and natural selection • accelerated by environmental change • can occur in rapid bursts, known as mass extinction events Background Rates of Extinction Germany: Insects declined 76 % in 30 yrs (Hallmann et al. 2018) Five Mass extinctions (> 50 % of species lost) Permian mass extinction 250 mya: ~83% of genera Cretaceous mass extinction 65 mya: ~71% of species Mass extinctions • Information from geology about large-scale and/or catastrophic events • Permian extinction: volcanoes? methane gas from deep sea? • Cretaceous extinction: a meteor? • Adaptive radiation of mammals occurred when? Lystrosaurus Speciation + Extinction = Tree of Life PLANTS flowering plants conifers ginkgos horsetails ferns FUNGI sac club fungi fungi cycads zygosporeforming fungi lycophytes bryophytes chlorophytes (stramenopiles) brown algae chrysophytes oomycotes ANIMALS arthropods chordates annelids roundechinomollusks worms derms rotifers flatworms cnidarians sponges chytrids green algae amoeboid protozoans red algae slime molds ? crown of eukaryotes (rapid divergences) PROTISTANS ciliates (alveolates) sporozoans dinoflagellates euglenoids kinetoplastids parabasalids (e.g., Trichomonas) ARCHAEBACTERIA diplomonads extreme (e.g., Giardia) Gram-positive bacteria halophiles methanogens cyanobacteria extreme thermophiles molecular origin of life EUBACTERIA spirochetes chlamydias proteobacteria But is it really a tree?