Exam 1 Flashcards
How did Charles Darwin describe evolution?
decent with modification
Levels of organization
cells tissues organs organ system organism
Evolution is both a … and a …
pattern, process
Pattern
observations about natural world
Process
mechanisms causing pattern of change
How did Darwin’s ideas challenge traditional views?
Many thought the earth was young and that species were unchanging; perfectly matched to their environment
Aristotle’s Csala Naturae
- Species do not change (they are designed by God and perfect) but there are some “affinities” among organisms
- Organisms are arranged on a ladder of increasing complexity (“scale of nature”)
Species do not change (they are designed by God and perfect) but there are some “affinities” among organisms
Aristotle’s Scala Naturae
Organisms are arranged on a ladder of increasing complexity (“scale of nature”)
Aristotle’s Scala Naturae
Carolus Linnaeus
Developed binomial nomenclature
Binomial nomenclature
two part naming system (Genus species)
How did Carolus Linnaeus name organisms?
Based on physical characteristics (morphology) and did NOT describe/support evolutionary relationships
What did Darwin argue that classification should reflect?
Evolutionary relationships
Carolus Linnaeus’s classification system
species were grouped along with similar species into increasingly general categories
Why did Linnaeus believe adaptations occurred?
the Creator had designed them for a purpose
George Cuvier
Developed Paleontology
Developed Paleontology
George Cuvier
Paleontology
the study of fossils
The older the strata (rock layer)…
the more dissimilar its fossils were to current life-forms
What did Cuvier attribute extinctions to?
catastrophic events
What did Cuvier speculate?
repopulation was by immigration (opposed evolution)
What do some scientists believe?
great changes can happen via slow but continuous processes
James Hutton and Charles Lyell
Geologists who stated that changes in Earth’s surface can result from slow continuous actions
Geologists who stated that changes in Earth’s surface can result from slow continuous actions
James Hutton and Charles Lyell
What did Hutton determine?
The Earth is millions of years old (rather than a few thousand)
What ideas were Darwin’s thinking influenced by?
- Fossil record
2. Idea of slow and continuous processes producing biological changes (evolution)
Jean-Baptiste de Lamarck
French biologist
What did Jean-Baptiste de Lamarck suggest?
life evolves
what mechanism did Jean-Baptiste de Lamarck propose?
- ) use and disuse
- ) inheritance of acquired characteristics
- ) innate drive for complexity
Use and disuse
the more you use, the stronger it becomes
Inheritance of acquired characteristics
Lamarck thought traits were aquired over a lifetime and that they could be heritable
Jean-Baptiste de Lamarck’s hypothesis
was testable, but wrong
followed the scientific process
Charles Darwin
English naturalist and geologist who was fixated on adaptation and speciation
Who was Charles Darwin protege of?
botanist John Henslow
Who heavily influenced Darwin?
Lyell and Hutton
HMS Beagle
Darwin collected speciments and record observations
What did Darwin observe on the HMS Beagle?
- ) fossils resembled living species
2. ) living species resembled those from nearby regions
What did Darwin hypothesize?
species from S. America colonized the Galapagos and speciated on the islands
What did Darwin focus on?
Adaptations
Adaptation
inherited characteristics of organisms that enhance their survival and reproduction in specific environments
What are adaptation and speciation explained by?
natural selection
Natural selection
individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits
individuals that have certain inherited traits tend to survive and reproduce at higher rates than other individuals because of those traits
natural selection
Alfred Russel Wallace
independently came up with the idea of evolution by natural selection
Origin of Species by Means of Natural Selection
published by Darwin in 1859
published by Darwin in 1859
Origin of Species by Means of Natural Selection
What did Darwin’s book explain?
unity and diversity of life, as well as match between organisms and environment
Descent with modification
species gradually aquire modifications that fit them to current environment, which leads to diversification
species gradually aquire modifications that fit them to current environment, which leads to diversification
Descent with modification
What is the history of life like?
a branching tree from a common trunk (ancestor)
What are morphological gaps in the branching tree explained by?
extinctions
What is the crafted argument of Darwin’s book?
- Artificial selection by humans
2. Observations and inferences from nature
Observation #1 from Darwin’s argument
Members of a population vary in inherited traits (behaviors can be inherited as well)
Artificial Selection
humans choose the traits in plants and animals that they want (i.e. dog breeds)
Observation #2 from Darwin’s argument
All species can produce more offspring than their environment can support, and many of these offspring fail to survive and reproduce
Inference #1 from Darwin’s argument
Individuals whose inherited traits give them a higher probability of surviving and reproducing tend to have more offspring
Inference #2 from Darwin’s argument
This unequal ability of individuals to survive and reproduce will lead tot he accumulation of favorable traits in the population over generations
Conditions for natural selection according to Darwin (when occuring together, these conditions yield evolution b natural selection)
- ) there must be a variation of traits in a population
- ) variations must be heritable
- ) different variants have different rates of survival
Examples of Natural Selection
- Darwin’s finches
- Industrial melanism in the peppered moth (biston betularia)
- Pathogen resistance to drug treatments
- Pest resistance to insecticides (includes crop pest and disease vectors such as mosquitoes)
Darwin’s finches
Studied finches on the Galapagos Islands, which experience huge yearly variation in rainfall
What else did Darwin study in regards to the finches?
beak size varies, and is genetically-controlled and heritable
What occured in the Galapagos Islands in 1976-78?
the islands experienced a drought that killed 85% of the finches
Explain why the beak sizes change
Finches eat smaller seeds during dry years, increasing the frequency of large seeds. This produced very strong selection for large beaked birds and some selection for really small beaked birds that were capable of eating very small seeds that most couldn’t handle
This led to the offspring of the finches having larger average beak size
This led to the offspring of the finches having larger average beak size
Explain the peppered moth
The peppered moth has both a white form and a dark form. During the industrialization era, air pollution increased and there was soot all over the trees. The dark moths went from 1% to 98% of the population in 50 years. As pollution decreased, lichen began growing on the trees, which allowed the white peppered moth better camouflage
Describe pathogen resistance to drug treatments
Drug resistant bacteria are becoming more common because the bacteria that are resistant to prescribed antibiotics reproduce. The offspring will then also carry the trait that causes them to resist
Pest resistance to insecticides (includes crop pest and disease vectors such as mosquitoes)
rapid human-induced changes in the environment lead to strong selection and a faster rate of evolution than would otherwise occur
What does natural selection act on?
The individual
At what level does evolution occur at?
the population level
Evolution is not…
goal directed (it’s chance), nor is it progressive
Four types of data that documents pattern of evolution
- Direct observations
- Homology-similarity resulting from common ancestry
- The fossil record
- Biography
Direct observations
Soapberry bug, MRSA
Soapberry bug
fed on native plants in Florida, fruits of each plant differs, bugs in S. Florida have long beaks, bugs in C. Florida have short beaks
MRSA (Methicillin Resistant Staphylococcus aureus)
became resistant to penicillin, then methicillin. Antibiotic resistance spreads faster than antibiotics have been discovered
Natural selection donly removes what?
Variation (does not create variation)
Natural selection can only work with what?
existing variation of the population
Homology
similarity resulting from common ancestry
Homologous structures
anatomical resemblances that present variations on a strucural theme present in a common ancestor
Vestigial strucures
remnants of features that once served important functions in organism’s ancestors
Convergent Evolution
independent evolution of similar features in different lineages (as opposed to resemblace due to homologies)
Analogous traits
similar function, but not common ancestry
Homologous traits
common ancestry, but not necessarily similar function
Allopatric speciation
Gene flow is interrupted or reduced when a population is divided into geographical subpopulations
Sympatric speciation
Speciation takes place in geographically overlapping population. Gene flow is reduced by factors other than geographic speciation
How does allopatric speciation occur?
subpopulations evolve independently through mutation, natural selection, and genetic drift
Types of Allopatric speciation
- Definition of barriers depends on the organism
- When individuals colonize new areas
- Reproductive isolation
How can reproductive isolation arise?
a by-product of genetic divergence
Microevolution
consists of changes in allele frequency in a population over time
Macroevolution
broad patterns of evolutionary changes above the species level
Speciation
process in which one species splits into two or more species
Speciation is the focal point of evolutionary theory and…
forms a conceptual bridge between micro and macro evolution
Species
Latin for “kind” or “appearance”
Hybrids
the offspring of crosses between members of different species
Biological species concept defines species as…
a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring
Aspects of biological species concept
- Gene flow between populations holds a species together genetically
- Reproductive isolation
Reproductive isolaltion
biological factors (barriers) that impede two species from producing viable, fertile offspring
Types of reproductive isolation
- Prezygotic barriers
2. Postzygotic barriers
Prezygotic barriers
“before the zygote” -block fertilization
Types of prezygotic barriers
- Habitat isolation
- Temporal isolation
- Behavioral isolation
Habitat isolation
breed in different places in the same range
- not isolated by obvious barrier; rarely encounter each other
Temporal isolation
breed during different times of the day, different seasons, or years
Behavioral isolation
courtship rituals and other behaviors enable mate recognition and prevent breeding
After Mating Attempt, Prior to Fertilization
- Mechanical isolation
2. Gametic isolation
Mechanical isolation
mating attempted, but morphological differences prevent completion
Gametic isolation
sperm of one species may not be able to fertilize the eggs of another species
Postzygotic barriers
“after the zygote” -contributes to reproductive isolation after formation of hybrid zygote
Types of postzygotic barriers
- Reduced hybrid viability
- Reduced hybrid fertility
- Hybrid breakdown
Reduced hybrid viability
genes of different parent species interact in ways that impair development and survival
Reduced hybrid fertility
hybrid survives, but is steril
Hybrid breakdown
first generationviable and fertile, but when mate with each other or either parent species, offspring are feeble or sterile
Limitations to Biological Species Concept
- cannot be bapplied to fossils
- cannot be applied to asexual organisms
- emphasizes absence of gene flow, but gene flow can occur between distinct species
Morphological species concept
defines species by strucural features
What does the morphological species apply to
- sexual and asexual species
2. fossils
What does morphological species concept rely on?
subjective criteria (debatable)
Examples of subjective criteria
Monarch and Viceroy
Ecological species concept
defines species in terms of its ecological niche
Niche
species “role” in environment defined as the set of conditions in which a viable populaiton can be maintained
What does niche apply to?
sexual and asexual species
What does niche emphasize?
the role of disruptive selection
Regions with many geographic barriers typically have…
more species than do regions with fewer barriers
Reproductive isolation between populations generally…
increase as the distance between them increases
Reproductive barriers are…
biological in nature; physical separation is not a biological barrier
In sympatric speciation, gene flow is reduced by…
non-physical barriers such as polypoidy, sexual selection, and habitat differentiation
Polyploidy
the presence of extra sets of chromosomes due to accidents during cell division
What is polypoidy more common in?
Plants than animals
What can a polypoidy produce?
new biological species in sympatry within a single generation
Sexual selecion
can drive sympatric speciation if females are choosing mates based on physical characterists
Habitat differentiation
- Sympatric speciation can also result from the appearance of new ecological niches
- Sub population explloits a new habitat or resource not used by the parent population
Types of sympatric speciation
- Polyploidy
- Sexual selection
- Habitat differentiation
In allopatric speciation…
geographic isolation restricts gene flow between populations
In sympatric speciation…
a reproductive barrier isolates a subset of a population without geographic separation from the parent species
Hybrid zone
a region in which members of different species mate and produce hybrids
What can a hybrid zone be?
a single band where adjacent species meet
What can changes in environmental conditions result in?
the relocation of existing hybrid zones or the production of novel hybrid zones
What can breeding between hybrids and parent species result in?
the transfer of alleles from one parent species to the other
Three possible outcomes when closely related species meet in a hybrid zone
- Reinforcement
- Fusion
- Stability
Reinforcement
Strengthening of Reproduction Barriers
- hybrids less fit
- natural selection stregthens prezygotic barriers
- overtime hybridization decreases
Fusion
- Hybrids are as fit as parents
- Can be substantial gene flow between species
- If enough reproductive barriers are weakened and parent species can fuse into a single species
Stability
Hybrids continue to be produced because extensive gene flow from outside the hybrid zone can overwhelm selection for increased reproductive isolation inside the hybrid zone
