Chapter 22 Descent with Modification: A Darwinian View of Life

40 vocabulary flashcards covering key terms and concepts from the Darwinian view of life lecture notes.

Descent with modification

--Used to describe Darwin’s view of life

—The Darwinian idea that all organisms are related by common ancestry and accumulate differences over generations. This has given rise to the diversity of life!

Evolution

The process by which species accumulate differences from their ancestors as they adapt to different environments over time; includes pattern and process.

Natural selection

-A mechanism in which individuals with certain inherited traits tend to survive and reproduce at higher rates due to those traits; traits become more common in a population over generations.

-INCREASES the FREQUENCY of adaptations that are favorable to an environment.

-DOESN’T CREATE NEW TRAITS: Alters traits that are already there.

• INDIVIDUALS DO NOT EVOLVE; IT IS THE POPULATION THAT EVOLVES OVER TIME.

Adaptation

An inherited trait that increases an individual's chances of surviving and reproducing in a given environment.

Unity of life

All organisms are related by descent from a common ancestor.

Diversity of life

The great variety of life forms resulting from branching descent and accumulation of modifications.

Common ancestor

An ancestral species from which different lineages diverge.

Homologous structures

Anatomical features in different species that share a common ancestry and a similar structural plan.

• EX: Bat wings→whale fins→cat arms→human arms are all the same phalanges.

Analogous structures

Structures serving similar functions in different species but without a shared ancestry; result of convergent evolution.

Convergent evolution

Independent evolution of similar traits in unrelated groups due to similar environmental pressures.

Fossil record

Evidence from fossils showing the history of life, including extinct lineages and transitional forms.

Biogeography

-The study of the geographic distribution of species provides evidence of evolution and continental drift like Pangaea

Endemic species

Species that occur in a particular region and nowhere else.

-EX: Australia has the most marsupials (kangaroos). The US only has one (possums).

Strata

Layers of sedimentary rock that preserve the sequence of deposition and fossils.

Sedimentary rock

Rocks formed from accumulated sediment laid down in layers.

Binomial nomenclature

Linnaeus's two-part naming system for species (genus and species).

Scala naturae

The ancient concept of a linear ladder of increasing complexity (the Great Chain of Being).

Fixity of species

Belief that species are unchanging over time.

Lamarck

Early evolutionary thinker who proposed use/disuse and inheritance of acquired characteristics.

Use and disuse

Idea that body parts used become stronger, while unused parts deteriorate.

Inheritance of acquired characteristics

Lamarck's idea that acquired traits can be passed to offspring (not supported by evidence).

Darwin

British naturalist who proposed natural selection as the mechanism of evolution.

The Origin of Species and the IDEAS

Darwin's 1859 work proposing evolution by natural selection in three broad observations:

• The unity of life

• The diversity of life

• The ways organisms are suited to life in their environments

-Essentially, all organisms are related by descent from a common ancestor. PHYLOGENETIC TREE!!

Alfred Russel Wallace

-Naturalist who independently conceived natural selection; prompted Darwin's joint consideration and publication.

-Sent Darwin a manuscript describing a nearly identical hypothesis of natural selection.

HMS Beagle

The voyage on which Darwin studied species and formed key ideas about evolution.

Malthus

Economist whose Essay on Population influenced Darwin's idea of struggle for existence.

Pattern vs process

Pattern refers to the data showing evolution; process refers to the mechanisms causing change.

Direct observations

Empirical evidence of evolution, such as observed natural selection and rapid adaptations.

MRSA

Methicillin-resistant Staphylococcus aureus; example of rapid bacterial adaptation under antibiotic pressure.

Artificial selection

Human-directed selection and breeding to produce desirable traits.

Fitness

Reproductive success; the contribution of an individual’s genes to the next generation.

Darwin’s Inference #1

Individuals with advantageous heritable traits tend to leave more offspring.

Darwin’s Inference #2

Unequal survival and reproduction leads to the accumulation of favorable traits in a population.

Homology

-Similarity due to shared ancestry, often reflected in anatomy or DNA.

Comparative embryology

-A study of embryonic development across species revealing homologous features.

-HOX genes; one gene that causes a feature or not. All or nothing

-EX: All vertebrate embryos have a post-anal tail and pharyngeal arches (tailbones)

Pangaea

-Ancient supercontinent from which modern continents drifted apart.

Evolutionary trees

-Diagrams that depict hypothesized relationships among groups with branching patterns.

-Can be made using different types of data, EX- anatomical and DNA sequence

-"Tree of life”: A branching diagram illustrating evolutionary relationships among species.

Geologic time

The vast timescale over which Earth’s rocks and life have evolved, inferred from fossils and rock layers.

Theory

A well-supported, comprehensive explanation that integrates a broad range of observations.

Charles Darwin

-British naturalist who proposed natural selection as the mechanism of evolution. He authored "The Origin of Species" in 1859. His ideas were developed during his voyage on the HMS Beagle and were influenced by Malthus's work on population.

-Reasoned that the Earth is older than we think (a few thousand years)

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Alfred Russel Wallace

A naturalist who independently conceived natural selection, which prompted Darwin's joint consideration and publication of their findings.

Jean-Baptiste Lamarck

An early evolutionary thinker who proposed the concepts of use/disuse (the idea that body parts used become stronger, while unused parts deteriorate) and the inheritance of acquired characteristics (idea that acquired traits can be passed to offspring, though not supported by evidence). EX: Giraffe necks elongated over time for a reason.

Carolus Linnaeus

-Developed a nested classification system grouping similar species into increasingly inclusive categories

-Creator of binomial nomenclature, a two-part naming system for species including genus and species. (EX: Homo sapiens)

Aristotle

-An ancient Greek philosopher associated with the concept of "Scala naturae," a linear ladder of increasing complexity also known as the Great Chain of Being.

-Believed that species were fixed (unchanging)

Descent

Shared ancestry, resulting in shared characteristics

Modification

Accumulation of differences

Georges Cuvier

-Largely developed the study of fossils. Observed that older strata contain fossils less similar to current organisms than more recent strata. AKA Paleontology.

-Speculated that boundaries between strata represent sudden catastrophic events.

Charles Lyell

Proposed that the same geologic processes operate today as in the past, at the same rate

James Hutton

Proposed that Earth’s geologic features were formed gradually. EX: Valleys being formed by rivers.

Thomas Malthus

• Wrote about the capacity of human populations to increase faster than critical resources. Darwin recognized this capacity in all species.

• ONLY A FRACTION of offspring complete development and reproduce; the rest are starved, eaten, diseased, etc.

Artificial selection

• The way humans modify species: breeding individuals with only desired traits.

• Darwin noted that humans have modified other species by selecting and breeding with desired traits. EX Cabbage, kale, brussel sprouts, broccoli, etc.

Four types of data that document the pattern of evolution

-Direct observations

-Homology

-Fossil Record

-Biogeography

Two examples that provide evidence for natural selection in response to introduces species and the evolution of drug-resistant bacteria

-The bacteria Staphylococcus a. is commonly found on people (Staph infection)

-One strain (MRSA) is a dangerous pathogen

Convergent evolution*****

The evolution of similar (or analogous) features in distantly related groups.

EX: A flying squirrel from N. America and a flying squirrel from S. America both develop webbed arms due to their environment and adaptation….. this does not mean they are related mammals.

Microevolution

The change in allele frequencies in a population over generations; is evolution at its smallest scale.

Three mechanisms that can cause allele frequency change:

1. Natural selection- adaption to the environment

2. Genetic drift- chance events alter allele frequencies

3. Gene flow- transfer of alleles between populations

Gregor Mendel

Work on pea plants provided evidence if genetic variation (including discrete heritable genes).

Genetic variation

The differences in genes or other DNA sequences among individuals.

Allele

one of two or more alternative versions of a gene that arises from a mutation or variation in the DNA sequence. EX: Big T or little t in a punnet square (Tt).

Phenotype