The Evolution of Life Flashcards
What is biology?
field of science, concerned with the study of life
Method of science
Examine how pieces of nature follow patterns and attempt to understand the processes that create those patterns
Hypothesis
a proposed expectation for specific observations (patterns) usually involving underlying processes
Predictions
Based on hypothesis what would you expect to see in a model system? Predictions need to be measured and need to be correct if the hypothesis is valid
Theory of evolution by Natural Selection pattern
species evolved, species adjacent to each other by either space or time are more similar than those that are more distant.
Species, are related by ancestry due to common decent.
Theory of Evolution by Natural selection Process:
Natural selection, Heritable variation in certain traits leads to improved reproductive success for some individuals.
What is population thinking?
(Theory of Evolution by Natural Selection)
-Population is a group of the same species located in the same area.
-Individuals in population vary, evolution occurs because individuals w certain traits have more offspring than others.
What is the theory of special creation?
Pattern: species are independent and unchanging
Process: species created by god
who thinks “Every species was a reflection of a perfect essence or type that was unchanging.
Typological thinking”
Plato (c.427-347 BCE)
Who “Orders organisms into a scale of nature “Great chain of Being”
Species were fixed types on a hierarchy
Rocks-> plants-> inverts-> animals-> Human-> angel -> God”
Aristotle (385-322 BCE)
What did Jean Baptiste Lamarck do?
Made the first scientific theory of evolution. Organisms progressively evolve up the chain of being, becoming more complex overtime
Process:
Inheritance of acquired characteristics. Organisms phenotype, changes in response to environmental and these changes pass on to offspring
Darwinian Revolution
overtime idea of species, unchanging, evolution NOT progressive.
-switch from typological thinking to population thinking
-Empirical prediction could be tested
Darwinian evolution
Decent with modification, change overtime produced modern modified species from ancestral species.
Prediction:
-species change overtime
-species are related by common ancestry
What is Evidence for evolution?
- Change through time
-Geologic Record
-Extinction
-Transitional forms
-vestigial traits - Species are related through common ancestry
-Biogeography
-Homologies
-Genetic homology
-Developmental homology
-Structural homology
what is the geologic record?
fossils - traces of organisms that lived in the past
Fossil record - fossils found and described in the scientific literature
Fossils were initially organized based on relative age
Sediment (sand,silt,Mud) laid down from erosia, under pressure sediment turns into rock (sandstone, mudstone)
Animal skeletons deposited with sediment
Laid down in layers -younger layers on top of older layers
age of the earth is about 4.6 billion years
-radioactive decay used to date the earth
Stable, consistent rates of decay from “parent” atoms to “daughter” atoms
Measure the ration
Earliest fossils- around 3.4-3.6 billion years
What is extinction?
99% of all species that have ever existed are extinct
These extinctions have occurred throughout history.
-Darwin interprets extinction as evidence that
1. species change overtime
2. extinct and living forms were related and represent ancestors and descendants
What are Transitional forms?
Features:
Are traits in fossils that are intermediate between ancestral and derived species.
-Provides us with evidence of change overtime (fins-> terrestrial limbs)
what are vestigial traits?
ex. Trail bone, goose bumps, wisdom teeth, reduced wings in penguins, eye sockets in eyeless fish.
Traits that Have no function today but was used in the past.
Reduced or incompletely developed structure with no or reduced function but are clearly related to functioning structures in other species.
What is Biogeography?
Geographic distribution of species
Tend to have more striking similarities among island species:
-Mocking birds of Galapagos are highly similar, but different islands have different species
-Share a common ancestor
-Supported by DNA analysis
What are Homologies?
Similarity that exists in species descended from a common ancestor
What is genetic homology?
A similarity in DNA/RNA nucleotide sequences or amino acid sequences
What is developmental homology?
Similarities in embryonic form or developmental processed due to inheritance from a common ancestor.
Similarity of embryonic “traits”
What is structural homology?
Similarities in adult organismal structures due to inheritance from a common ancestor
Vertebrates have a common structural plan in limb/bones
Homology exists because vertebrates evolved from ancestral tetrapod with the same general arrangement of bones and limbs.
are all similarities homologous?
Key point: Common ancestry predicts homology
Example of convergent evolution: independent evolution of similar traits in distantly related individuals due to adaptation to similar environments and ways of life.
If similar traits did not exist in common ancestors they are Analogous or Homoplasy
What are Darwins four postulates
- Individuals vary in their traits
- Some of these traits are heritable - they can be passed on to offspring
- In each generation, many more offspring produced than can survive.
- Only some will survive long enough to reproduce
- Some will produce more offspring than others
- Individuals with certain heritable traits are more likely to survive and reproduce.
- Natural selection occurs when individuals with certain traits produce more offspring than those without those traits.
- Individuals are selected naturally by the environment
What is biological fitness?
The ability of an individual to produce surviving, fertile offspring.
What is adaptation?
A heritable trait that increases an individuals fitness and particular environment relative to others lacking that trait.
What is selection?
Differential reproduction as a result of heritable variation.
What are genetic mechanisms?
What controls the inheritance of traits?
- Different forms of genes are called alleles
- Different alleles code for different traits (some are more successful then others)
Allele frequency will change from one generation to the next.
what is acclimatization?
individuals’ phenotype can change in response to environment (not genotype), but these changes are not heritable
why is Evolution not progressive?
organisms do not necessarily get bigger, stronger, smarter or more complex over time.
Complexity does often increase, but it is not inevitable (vestigial traits)
Adaptations do not occur because organisms need them
why are traits not always adaptive?
- Selection can’t optimize all aspects of a trait
- Mutations must occur and are random
What are fitness trade-offs?
- selection is going to act on multiple traits concurrently, leading to a compromise in fitness.
- Number of offspring -> trade off = offspring survival, Offspring reproduction, smaller offspring (body size), individual survival (not enough nutrients, etc.), parental care
what does it mean when traits are historically constrained?
all traits evolve from previously existing traits - constrained by history
Apoptosis is a developmental process defined as ____.
Programed cell death
Apoptosis is programmed cell death, a carefully regulated and normal
^part of development
