Classifying biologyQuestion: Which is the most similar?

-classify by looking at evolutionary relationships

Answer: croc and pigeon

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MacroevolutionClassification: categorize organisms to understand evolutionary relationships

Kingdom: Animalia

Phyla: Chordata

Class: Mammalia

Order: Primate

Family: Hominidae

Genus: Homo

Species: sapiens

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HomologiesHomologous traits: similarities due to common descent

E.g., birds, bats, mice, crocs all have four limbs

Contrast with analogies: similarities due to common function

Classifying biologyHomologies: similarities based on a common ancestor

vs

Analogies: similarities due to common function

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Two types of homologiesAncestral traits: similarities in many taxonomic groups inherited from a remote ancestor

Derived traits: have been modified from the ancestral conditions

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Homologies some more

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Schools of classificationEvolutionary systematics: hypothesizes about ancestor-descendant relationships over time

-use phylogenetic trees

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Schools of classificationCladistics: use shared derived traits to identify new speciesClades: lineages sharing a common ancestor

-Anthropologists mostly use cladistics

Evolutionary Systematics: explains ancestor-descendant relationships over time

Cladistics: uses shared derived traits to classify new species-no time

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Compare and contrast classification systems

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Generalized vs specialized traits

Generalized traits adapted for many functions

Specialized traits arise during adaptive radiation -generalists specialize to niches

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Macroevolutionary processesAdaptive radiation: rapid expansion and diversification of groups into empty ecological niches

Niche: a species place in an environmental setting

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Species concepts

Biological species concept: groups of interbreeding individuals that are reproductively isolated

Speciation occurs if-geographic, behavioral, anatomical isolation-natural selection is acting on populations-highly differential niches

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Species concepts

Paleospecies: groups of fossil organisms that are assigned to the same species.

Variation over time needs to be considered when classifying paleospecies

Intraspecific: variation within species

Interspecific: variation between species

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Fossils: remains of organisms preserved over time

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Fossils: remains of organisms preserved over time*Mineralization: organic material chemically turned into rock

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Fossils: remains of organisms preserved over time

*Mineralization: organic material chemically turned into rock

*Organisms are trapped in tree resin/an anoxic environment

*Mineralization: organic material chemically turned into rock

*Organisms are trapped in tree resin/an anoxic environment

*Imprints of tracks or leaves in hardened mud

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Fossils: remains of organisms preserved over time

Video questionAttendance: Write your name on a piece of paper and respond to the following question:

Identify at least three examples of the different concepts discussed in the course so far.

E.g., Homologies, mitosis, meiosis, natural selection, selective pressures, genetic drift, gene flow (migration), mutation, etc.

https://youtu.be/StqZI9pMq0U

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Paleozoic era (570-225 mya)-first vertebrates emerged-first mammal-like reptiles-Pangaea formed

Mesozoic era (225-65 mya)-Age of dinosaurs

Cenozoic era (65-0 mya)-Age of mammals

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Continental drift: movement of continents on Earth's surface-causes mountain building, volcanic activity, earthquakes, etc

Late Paleozoic to Late Mesozoic-plate tectonics caused reproductive isolation

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Mesozoic to CenozoicLate Mesozoic era: Age of Dinosaurs-earliest mammals

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Cenozoic era: age of the mammals

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Mesozoic to CenozoicLate Mesozoic era: Age of Dinosaurs-earliest mammals

Cenozoic era: age of the mammals

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Three modern mammalian subgroups

Monotremes: most ancestral mammals, e.g., they lay eggs

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Three modern mammalian subgroupsMarsupials: immature birth; development continued in pouch

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Three modern mammalian subgroupsPlacental: in utero development

Paleozoic era (570-225 mya)-first vertebrates emerged-first mammal-like reptiles-Pangaea formed

Mesozoic era (225-65 mya)-Age of dinosaurs

Cenozoic era (65-0 mya)-Age of mammals

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Mammalian shared derived homologies

-Endothermic

-Heterodont dentition

-Placental

-Complex brains andflexible behavior