Flashcards in Chapter 4 Deck (99):
When all members of a species die
the pace at which species go extinct due to gradually changing environments.
Most extinctions occur as part of this.
Background extinction rate
Earth has witnessed five ___________ in the last 600 million years. During these periods, many species went extinct in a short time.
suggests that meteorites or comets caused some mass extinctions.
The debris suspended in the atmosphere after a collision dramatically changed the environment, leading to the extinction of many species.
(Earth’s shifting land masses) also might explain mass extinctions.
= early life
= age of dinosaurs
= era of mammals
= the cretaceous (K) – tertiary (T) boundary
The KT boundary
A layer of sediment containing high levels of iridium
The K-T boundary
the study of interactions between biotic and abiotic elements
All living components
• temperature, light, water, minerals, air
A group of organisms inhabiting the same area
:an individual living thing
: the study of how populations interact and change in response to their environment
: the study of organismal adaptations that allow it to live in its environment
: interacting populations that inhabit a particular area
: the study of population interactions and how these dynamics affect community structure
: the nonliving environment and all the living organisms within a certain area
: the study of energy flow and nutrient cycling in a given environment
: the global ecosystem
– All of the ecosystems on the planet
– Most complex level in the ecological hierarchy • Atmosphere down to the deepest ocean depths
– Immediate responses to environmental changes – May be behavioral or physical
– Short term and quickly altered
– Longer term responses
– Includes thicker fur in winter (winter coat), increased or decreased metabolism, increased fat stores, etc.
: the way individuals are spaced within a geographic range
Patterns of dispersal
: individuals aggregated in patches
: individuals are uniformly spaced
: individuals are spaced in an unpredictable way
When two (or more) species in a community rely on similar resources
Two species that compete for the same niche cannot coexist
-the superior competitor will exclude the weaker
Competitive exclusion principle
-Both are top predators
-hyenas have a wider
Lions and Hyenas
Basis for a lot of evolutionary adaptation
- really neat adaptations
-Eat and avoid being eaten
-Prey usually ahead of the predator evolutionarily
When one species lives in or on another species
(Sym rel) when one organism benefits while the other is harmed
(Sym rel) when one organism benefits but the other is not harmed in the interaction
(Sym real) when both organisms benefit
Any episode that damages or disrupts a biological community
- storms, fire, flood
-* most communities are in some stage of recovery from this
Diversity is highest at intermediate levels of disturbance
Intermediate disturbances hypothesis
Biodiversity has three main components
The loss of species also means loss of _______ and _____ diversity
Human ______ allows us to recognize the value of biodiversity for its own sake
Practical benefits to humans with species diversity
The enormous genetic diversity of organisms has potential for great human benefit
Drugs, economic impact of tourism, our success
How are we impacting the environment
Burmese pythons in Florida.
The cues that animals use are no longer tightly linked to true habitat quality and an _____ arises where individuals will prefer now unsuitable habitat.
-can arise for a variety of reasons including amplification of cues.
Absorb and emit radiation in the atmosphere
Current CO2 levels higher than in the past ______ years
Caused a dramatic rise in CO2
= (#births – #deaths)÷population size
• Rate of increase (r)
is just change in a population over time
• Specifically it is change in the allele frequencies in a population over time
– So populations are always
What evidence, that you know of, do we have for evolution?
– Fossils– Genetic similarity– Biogeography– Observational changes in populations (e.g. antibacterial resistance, DDT resistance in mosquitoes)– Experimental evolution– Selective breeding.
– And more
many species were created, then portions were destroyed and fossilized in successive catastrophes
– Living organisms are modified as they grow
• Through use of their own bodies
• Through changing environmental pressures
– Modifications passed on to offspring
• Problem with this idea?
• If you lost your right leg in a logging accident then your kids would be born with no right leg
• All body builders’ children should be HUGE!
Inheritance of Acquired Characteristics
– Individuals with certain heritable traits leave relatively more offspring
– Became known as “Evolution by Natural Selection”
• Wallace got screwed
– This is what’s commonly referred to as “survival of the fittest”
• A poor approximation of the true meaning
• The most studied mechanism of evolution
• There are others – Mutation– Genetic drift
• Commonly conflated with evolution
– Observation 1: Populations produce far more offspring than the environment can support
• Overproduction leads to competition
– Observation 2: Individuals in a population vary in many traits
• Successful individuals pass on their traits to offspring
– Inference: Modification in organisms is due to differential survival and reproduction
• Most fit organisms make the most babies
• Most fit organisms’ genes in greater numbers in the next generation
How natural selection developed
Evidence of Evolution
Fossil record, missing links, biogeography, capmparitive anatomy-homologous structures-analogous structures,
favors individuals with an extreme value for a trait
favors individuals at both extremes of a trait
favors individuals with the average value for a trait or culls individuals with extremes of the trait
a group of individuals of the same species living in the same area at the same time
all the alleles of all the genes in all the individuals making up a population
Gene flow: movement of alleles into or out of a population
Structures with similar origin. Differ in design and function
Similar function. Different evolutionary history. Result of convergent evolution
Evidence of evolution
Comparative embryology( organisms go threw nearly identical developmental stages
Is a sorting process. Has no specific objective(it doesn’t want to make certain species, not goal directed
Individuals struggle to acquire limited resources
Competition for mates
Favors individuals with an extreme value for a trait
Favors individuals at both extremes of a trait
Favors individuals with the average value for a trait
Chance events change allele frequencies
Bottleneck effect-Over hunting
Founder effect- individuals colonies new ares
Preference for mates that are similar
Females are picky and choose a breeding partner
Female mate choice
Males compete for the attention of females
Not just about survival of the fittest! You got to make babies
Differential survival and reproduction
Two closely linked species become the most dominant force in each other’s evolution. Snake ,newts
Very common in pollination interactions
The sorting process that determines what characteristics are favored for mating. Selection administered by “choosier” sex(usually female)
More flashier males mean that they are fit because they survived despite there flashy traits.”honest advertisement”
Why are females typically the choosier sex?
More time invested
Females don’t choose mate, brightly colored, leave male with eggs, female mates with multiple males
Changes in the gene pool over successive generations
-alleles and genes
Formation of species , evolutionary novelty, diversification, mass extinction
Accumulation of changes gradually
Transforms the species,but does not create a new one
Splitting of a gene pool into separate pools.
Not genetic drift
*only pattern that increases the number of species
Current changes build on previous changes
*mutation provides raw material.
Source of change
Deals with species and how they come about and change over time.
The process by which new species form
(Category of speciation) species form due to geographic separation
(Category of speciation) species form in the geographic are.
-form due to behavioral or niche separation
-more common in plants
Similar traits evolving in separate species
-long history of evolutionary isolation
(Tempo of speciation) species gradually diverge as they require unique adaptations
(Tempo of speciation) periods of rapid change followed by long periods of little to no change, probably more common, *data suggests this led to the formation of different animal phyla. *not mutually exclusive.
*populations must remain isolated
(Maintaining species) two types of barriers.
1. Mechanisms that prevent mating.-geographic isolation
2.mechanisms that prevent successful hybrids.-Hybrid inviability
The pattern of continuously accelerating increase of population size under ideal unregulated conditions
Exponential growth model
Factors that limit population size as density increases.
Factors that limit population size regardless of density.
-climate/wether,-natural disasters, -human activities(pesticides,hunting, habitat destruction)