Chapter 5: Evolution of Biodiversity (APES)

pg 153 #1 How many species are estimated to exist on Earth? (a) 2 million (b) 8 million (c) 10 million (d) 30 million (e) 100 million

(c) 10 million

pg 153 #3 Phylogeny is (a) the number of evolutionary related species in an ecosystem. (b) the study of morphological traits. (c) the branching pattern of evolutionary relationships. (d) the process of evolution that creates new species. (e) the genetic biodiversity of a species.

(c) the branching pattern of evolutionary relationships.

pg 153 #2 Two savanna communities both contain 15 plant species. In community A, each of the 15 species is represented by 20 individuals. In community B, 10 of the species are each represented by 12 individuals; the remaining 5 species are each represented by 3 individuals.Which statement best describes the two communities? (a) Community A has the same biodiversity as community B. (b) Both communities have the same species evenness. (c) Community B has a higher species richness. (d) Community A has a higher species evenness. (e) Community B has a lower species richness.

(d) Community A has a higher species evenness.

Founder effect

A change in the genetic composition of a population as a result of descending from a small number of colonizing individuals. If a few individuals from a mainland population colonize an island, the genotypes on the island will represent only a subset of the genotypes present in the mainland population. As with the bottleneck effect, some genotypes will not be present in the new population.

Genetic drift

A change in the genetic composition of a population over time as a result of *random mating.* Can have a huge impact on the small population! (Small changes in small populations can have big effects)

Evolution

A change in the genetic composition of a population over time.

Mass extinction

A large extinction of species in a relatively short period of time. Organisms that can't survive through changes and adapt to their surroundings die out easily. 99% of the species that have ever lived on Earth are now extinct.

Evolution by mutation

A mutation can arise in a population and if it is not lost it may increase in frequency over time.

Gene

A physical location on the chromosomes within each cell of an organism.

Mutation

A random change in the genetic code produced by a mistake in the copying process. More likely to happen when DNA is being copied before mitosis/meiosis. Mutations can be passed down to next generation, and they can be beneficial.

Bottleneck effect

A reduction in the genetic diversity of a population caused by a reduction in its size. It means species are less able to adapt to future environmental changes. The original cheetah population didn't have spots. It went through 3-4 bottleneck events (each time whipping out a part of the population, meaning older genes were lost), meaning they now all have spots. They are now so similar, that they all look like twins. This is bad, because there is little genetic variation which can result in bad health and overall extinction.

Phenotype

A set of traits expressed by an individual.

Niche generalist

A species that can live under a wide range of abiotic or biotic conditions. (ex) Cockroaches, racoons

Niche specialist

A species that is specialized to live in a specific habitat or to feed on a small group of species. (ex) Panda bears

Adaptation

A trait that improves an individual's fitness.

Shannon's Diversity Index

Accounts for both species diversity and evenness. H ranges from 0-4.6 (0 means every species is the same, no biodiversity; 4.6 means evenly distributed species, high biodiversity) You won't need to do the calculation, the values will be presented to you, but you will be expected to understand the formula in terms of biodiversity. Lower value=less diversity.

Fitness

An individual's ability to survive and reproduce.

Genetically modified organism (GMO)

An organism produced by copying genes from a species with a desirable trait and inserting them into another species.

Distribution

Areas of the world in which a species lives.

Micro-evolution

Evolution below the species level

Macro-evolution

Evolution that gives rise to new species, genera, families, classes, or phyla.

Why are species richness & evenness important?

Knowing the species richness or evenness of an ecosystem gives environmental scientists a baseline they can use to determine how much an ecosystem has changed. If one community has 4 species (25% of every species present), and another community has 4 species (70% of 1 species and 10% of all the other species, the two communities are equally species rich but the first community is more species even. The community that has more of one trait and/or the other will be more bio-diverse and therefore more sustainable for much longer.

Geographic Isolation

Physical separation of a group of individuals from others of the same species.

Simpson's Diversity Index

Refers to any one of 3 closely related indices. It measures the probability that 2 individuals randomly selected from a sample will belong to the same species (or some category other than species). There are 2 versions of the formula for calculating D. Either is acceptable, but be consistent. The values of D range between 0-1. The higher the #=the more biodiverse.

How do we measure biodiversity?

The # of species in any given place is a common measure of biodiversity, but estimating the total # of species on Earth is a challenge. There are about 10 million species total, but scientists have classified 2 million species.

Phyogeny

The branching pattern evolutionary relationships. The more similar the traits of 2 species, the more closely related the 2 species

Genotype

The complete set of genes in an individual. They help determine the traits of individuals.

Extinction

The death of the last member of a species.

Sympatric speciation

The evolution of one species into two, without geographic isolation.

Sympatric speciation

The evolution of one species into two, without geographic isolation. In plants, it's been beneficially and led to tons of different types of plants. An increase in the number of chromosomes beyond 3 sets has led to a great deal of diversity in plants which has been great for human consumption.

Recombination

The genetic process by which one chromosome breaks off and attaches to another chromosome during reproductive cell division. The reason why siblings look different. Doesn't create new traits, just combines alleles differently, which can provide new immune defenses.

Range of tolerance

The limits to the abiotic conditions that a species can tolerate.

Gene flow

The process by which individuals move from one population to another and thereby alter the genetic composition of both populations. Think about migration and emigration! The FL Panthers were inbreeding b/c there weren't that many. The kink tail was a sign of a lack of good health (genetically). A group of panthers from Texas were brought to FL to create more genetic variation in the FL panther population which made them more healthy as a whole.

Evolution by artificial selection

The process in which humans determine which individuals breed, typically with a preconceived set of traits in mind. Has produced tons of livestock and pets. Agricultural crops are a result of careful breeding. But it can also produce unintended results such as herbicide resistance (killing weeds, and eventually some weeds resist the pesticide and they reproduce and eventually all weeds are resistant to the pesticide) *(ex) All dogs can be traced back to one wolf (ancestor)*

Evolution by natural selection

The process in which the environment determines which individuals survive and reproduce. All species produce an excess number of offspring. Only those offspring

Allopatric speciation

The process of speciation that occurs with geographic isolation.

Realized niche

The range of *abiotic & biotic* conditions under which a species actually lives.

Species Evenness

The relative proportion of individuals within the different species in a given area.

Reproductive isolation

The result of two populations within a species evolving separately to the point that they can no longer interbreed and produce viable offspring.

Fundamental niche

The suite of *abiotic* conditions under which a species can survive, grow, and reproduce.

Species Richness

the # of species in a given area