Biology Final Study Guide

Evolution

The process of biological change by which descendants come to differ from their ancestors.

Comparative embryology

Comparing embryos of different organisms can indicate they may have shared a common ancestor.

Homologous structures

•  Features found in different organisms that share structural similarities but may have very different functions. Evidence of divergent evolution. 

  • Ie. human arm, whale fin, bat wing

Analogous structures

• Structures that perform a similar function but are not similar in origin. Evidence of convergent evolution.

  • Ie. bat wing, bird wing, insect wing

Vestigial structures

• Remnants of once-important structures that gradually have lost all or most of their function over time. Provide clues to an organism's evolutionary past. (ie. appendix, wisdom teeth, tailbone or coccyx)

Cladogram

Branching diagram showing evolutionary relationships based on shared characteristics

Fossil Record

• A fossil is the preserved remains of an organism, or the trace evidence of an organism's existence in the past. ​ ​ Layers of rock form gradually over long periods of time, with more recent layers typically on top of older layers. Fossils that differ from each other slightly and are embedded in different layers of rock provide evidence for gradual change in species over time.

Comparative biochemistry

• Comparing the molecular makeup of an organism such as proteins, enzymes, DNA, and other body chemicals.  The greater the similarity, the more closely related the organisms are and the greater the likelihood they share a common ancestor.

Extinction

• The disappearance of an entire species (usually due to drastic changes in an ecosystem over a short period of time)

Adaptation

• A variation in a population that increases the chances of survival.

  • Ie. camouflage, bright colors, spines, armor plates, mimicry

Competition

• Struggle for resources took place in nature. 

  • The challenge is for each individual to be better at obtaining available resources, such as food, water, and shelter.

Natural Selection

• A gradual favoring of advantageous traits within a population.  A particular phenotype may allow individuals to survive longer and reproduce more efficiently, both of which increase the total number of offspring produced. Over time the phenotype becomes more prevalent.

Gene Pool

• The collection of alleles found in all the individuals of a population.

Allele Frequency

• The proportion of one allele, compared with all the alleles for that trait, in the gene pool. 

  • Formula: # of a particular allele / total # of alleles

Hardy-Weinberg Equilibrium

• refers to a population that is stable and not evolving. 

• Five conditions must be met for a population to be in equilibrium: 

  • no mutations

  • Very large population

  • No natural selection

  • No new genetic material is introduced

  • Individuals are equally likely to mate with any other individual in the population.

• Hardy Weinberg Equation

• p² (Homozygous Dominant) + pq (Heterozygous) + q² (Homozygous Recessive) = 1

Normal distribution

• A bell-shaped curve like the one shown on a normal distribution graph.

• The shape of the curve shows that the intermediate phenotype in the majority of the individuals is close to the mean average. 

Microevolution

• The observable change in the allele frequencies of a population over time. 

• Microevolution occurs on a small scale—within a single population.

Types of natural selection

• Stabilizing: Favors the intermediate phenotype

• Directional: Favors one extreme phenotype

• Disruptive or Diversifying: Favors two extreme phenotypes

Gene Flow

• The movement of alleles from one population to another. 

• Gene flow can cause a population to evolve.

Genetic Drift

• A change in allele frequencies due to chance

• Small populations are more likely to be affected by chance than large populations

Bottleneck Effect

• This is genetic drift resulting from an event that drastically reduces the size of a population. 

• Through genetic drift, some alleles can be completely lost from the gene pool and others can be fixed in the population, resulting in lower genetic diversity.

Founder Effect

• This is genetic drift that occurs when a small number of individuals become isolated from the original population and colonize a new area. 

• The founding populations each represent a distinct gene pool observed in the founding population. As a result, allele frequencies within the founding populations change from the original population, reducing genetic variation.

Sexual Selection

• The tendency to select males that will give their offspring the best chance of survival. 

• This difference in reproductive costs can make females choosier than males about mates. 

• Sexual selection occurs when certain traits increase reproductive success.

Speciation

• The rise of two or more species from a single existing species

Allopatric Speciation

• Speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration.

Sympatric Speciation

• The splitting of an ancestral species into two or more reproductively isolated groups without geographical isolation of those groups.

• Unique behavioral patterns & rituals can isolate species

Adaptive Radiation

• Speciation through the diversification of one ancestral species into many descendant species.

• Adaptive radiation typically happens quickly as species benefit from less competition, new niches, or specializations that give a selective advantage. 

• For adaptive radiation to take place, there must be adaptation by a species that leads to speciation.

Hybridization

• When two distinct, but closely related, species are able to successfully mate. 

• Sometimes, the features shown by the hybridized species fall within the range of characteristics shown by one or both of the original populations. 

• Over time, as the two species continue to interact with one another, they may become a single species.

Extinction of Species

• The elimination of a species from Earth 

• Extinction often occurs when a species as a whole cannot adapt to a rapid change in its environment.

Causes of Extinction

• Competition from other organisms in its current range.

• Extirpation, or local extinction, occurs when a species ceases to exist in a specific portion of their range but still exists elsewhere.

• Natural events and disasters such as climate change, earthquakes, volcanic eruptions, droughts, and floods can cause extinctions if species are unable to adapt to the new environment.

Background Extinctions

• Extinctions that occur continuously but at a very low rate. 

• Occur at roughly the same rate as speciation. 

• Typically affects one or a few species in relatively small areas. 

• Common and occurs due to factors such as disease, loss of habitat, or loss of a competitive advantage.

Mass Extinction

• More rare but have a larger impact on Earth's biodiversity. 

• Entire orders or families may be wiped out by mass extinction events. 

• Mass extinctions are thought to occur suddenly in geologic time, usually because of a catastrophic event such as an ice age or asteroid impact.

• Other causes of mass extinctions: 

  • Climate Change

  • Rising Sea Temperatures

  • Ocean Acidification

  • Extreme Weather Events

Responsive Behavior

• Stimulus: Anything that triggers a response.

  • Ie. We respond to cold temperatures by shivering

• Internal stimulus: Triggers a response to a change in an organism's internal environment.

  • Ie. infection. 

• External stimulus: Any change in the external environment that triggers a response.

  • Ie. temperature change.

Innate behavior

• Innate behaviors are passed from generation to generation without learning. 

• An innate behavior is performed correctly the first time an animal tries it, even when the animal has never been exposed to the stimulus that triggers the behavior.

• Instincts

Benefits of Behavior

• Increases survivorship, or the number of individuals that survive from one year to the next. 

• Increases an animal's fitness by natural selection. 

  • A behavior will be expressed if its benefits outweigh its costs. 

  • Behaviors that improve an individual's fitness will be passed onto future generations.

Social Interactions

• Social behaviors include any and all interactions between individuals of the same species. 

• Social groups interact in many ways, such as through communication, mate selection, and defense.

Communication

• Sharing or exchange of information is critical to the survival of individuals and groups, as well as for the species itself. 

• Vocalizations, plumage, songs, mutual grooming, and pheromone trails are all forms of communication.

Mate Selection

• Courtship displays are behaviors most often used by male members of a species to attract females. 

• Scientists theorize that females use courtship displays to judge the condition of their potential mate or the quality of his genes.

Defense

• Behaviors that are responses to threatening stimuli from the environment. 

• These various behaviors are meant to reduce harm to the individual. 

• Animals will often put themselves in harm's way to protect their young. 

Cooperation

• Behaviors that improve the fitness of the individuals involved.

• A group of organisms working together to accomplish a task.

Reciprocity

The idea is that one action will result in a future beneficial response.

Altruism

• Behavior in which an animal reduces its own fitness to help other members of its social group. 

• The animal appears to sacrifice itself for the good of the group.

Inclusive fitness

• Total number of genes an animal contributes to the next generation

Kin selection

• When natural selection acts on alleles that favor the survival of close relatives

Eusocial organism

• Population in which the role of each organism is specialized and not all of the organisms will reproduce.

  • Common examples of eusociality occur within the bees, ants and wasps. Colonies comprise one or more queens who lay eggs and these are tended by workers. Other workers are responsible for collecting food for the colony or defending it against predators.

Learned Behaviors

• Behaviors are actions that change with experience. Learning takes many forms, ranging from changes in behaviors that are largely innate to problem-solving in new situations. 

• Learning involves the strengthening of nerve pathways. Most behaviors are not simple reactions to stimuli using preset pathways in the animal's brain. Instead, they represent a combination of innate tendencies influenced by learning and experience. 

• Learning allows animals to quickly adapt to changes in their environment, increasing their ability to survive and reproduce.

Cultural behavior

• Behavior that is passed between members of the same population by learning and not natural selection.

Cultural transmission

• The behavior is taught to one generation by another.

• Ie. The transmission of birdsong in some taxonomic groups of birds is an example of cultural behavior

Factors that Affect Population Growth

• Renewable Resources

• Nonrenewable Resources

Human Impact on Air and Climate

• Air Pollution

  • Smog

  • Acid Rain

Climate Change

• Greenhouse Effect

• Greenhouse Gases

Human Impact on Water and Land

• Water Pollution

  • Point Source

  • Non Point Source

Managing Water

• Dams/Levees

• Wastewater Treatment

Impacts on Land

• Soil Erosion

• Deforestation

• Desertification

• Mining

Human Impact on Biodiversity

habitat loss, clearing land

Habitat Fragmentation

• Wildlife Corridors

Habitat Management

• Sustainable Development

• Protecting Habitats

• Protecting Endangered Species

Introduced Species/Invasive Species

• Managing Invasive Species

Overharvesting

• Overfishing

• Over Hunting

• Sustainable Hunting and Fishing Practices

Converting Energy

• Coverting Energy from Waste

• Burning Waste using Incinerators

• Making Biofuels from Waste

• Anaerobic Digestion of Biomass

Preventing Deforestation

• Wood Alternatives

Making New Habitats

• Green Roofs

Lowering Carbon Dioxide Emissions

• Negative Emissions

  • “Clean” coal

Decreasing Water Pollution

• Rainwater Harvesting Systems

• Wastewater Treatment

  • Water Filtration