biology - unit 3 topic 1

biodiversity

the range of different living things in a particular area or region in an ecosystem that can be described at varying levels (including the species and genetic diversity)

ecosystem

a self-sustaining unit consisting of the interactions between the species in a community and the environment

species

lowest taxon in classification - always italicised and combined with genus

what can biodiversity refer to

genetic, species and ecosystem

genetic diversity

the range of different genes within a species

species diversity

range of different species in an ecosystem

ecosystem diversity

range of different ecosystems in a particular location

what are the consequences for low biodiversity

inbreeding, vulnerability to disease, over-predation and ecosystem breakdown

what is an ecosystem composed of

all the living organisms (biotic factors) together with the physical environment (abiotic factors) in one particular area.

biotic factors

living components of an ecosystem, including animals, plants, fungi and bacteria

abiotic factors

the non-living components of an ecosystem, including the physical landscape, minerals and weather conditions.

how is light transferred into chemical energy

energy is initially transformed from light to chemical energy, through photosynthesis, and then transferred between organisms via tightly linked food webs.

species richness

the number of species present in an ecosystem

relative species abundance

the number of individuals present for each species in an ecosystem

percentage cover

- the percentage of the quadrant that a species takes up

percentage frequency

the percentage of quadrats in which a species appears.

Simpson's Diversity Index

the combined ratio of individuals in each species to the total individuals in an ecosystem - a quantitative measure of biodiversity

gives a number between zero (no diversity) and on (infinite diversity) while accounting for species richness and relative species abundance

what does relative species abundance enable

for ecosystems with one dominant species to be differentiated from more evenly distributed ecosystems.

how is an ecosystem considered healthier

if its species are similar in number

what is a limitation of quadrants

species tend to live together in communities and this may mean that although your quadrat is 80% closer, it may be the only clover in the ecosystem.

spatial scale

how much area a studied ecosystem covers

macro-level ecosystems

a large area of land or water and its inhabitants

meso-level ecosystems

a medium-sized area of land or water (typically a single location e.g. lake or desert) and its inhabitants

micro-level ecosystems

a small area of land or water (typically a single biome) and its inhabitants

predation

a species interaction which one species kills and eats another

competition

a species interaction in which two or more individuals compete for the same resources in the same area

what is the ratio of produces to first and second level consumers in biodiverse ecosystems

similar in biodiverse ecosystems, regardless of spatial scale.

:ess biodiverse ecosystems are skewed one way or another

what are some examples of abiotic factors

temperature, light intensity, rainfall, texture, pH of the soil or water and concentration of significant gases in the water or air.

are abiotic factors able to change the biodiversity of an ecosystem

each abiotic factor has the capacity to change the biodiversity of an ecosystem.

temporal scales

the time period over which an ecosystem is studied

why can species diversity vary

species diversity are often different at different times of day or year and can be due to natural or unnatural causes

diurnal

active during the daylight hours

can species interactions change over temporary scales

yes

can abiotic factors change over time

most factors do not naturally change

what has changed the abiotic factors

climate change has caused drastic changes to the long-term temperature of the macro-level ecosystems.

limiting factors

an aspect of the environment that restricts an organism's ability to live there

are biotic and abiotic factors also limiting factors

almost all biotic and abiotic factors are limiting factors to something else.

what do limiting factors mean for organisms

limiting factors do not mean that organism can't live there, it just means they would struggle to live there

taxonomies

a system of classification particularly biological; or the study of these systems.

hierarchy

a system categorised by the specific arrangement of information into 'layers'

what do the upper levels in hierarchies allow

the upper levels incorporate more information than the lower levels, which are more specific

what must scientist's do in order to classify organisms

they must emphasis major similarities

how can all living organisms be classified

on the basis of physical traits, reproductive methods and/or molecular sequences.

what does a standard taxonomy allow

the identification of already discovered organisms and absorbs information about new organisms

taxon

a level of hierarchical classification system, e.g. kingdom, family or species

what are the names of the major taxa

• Domain

• Kingdom

• Phylum

• Class

• Order

• Family

• Genus

• Species

  (Do Kids Prefer Candy Over Fresh Green Salad)

where is the DNA stored in members of domain Eukarya (eukaryotes)

their DNA is contained within a nucleus and there are membrane-bound organelles.

what members are included in domains Archaea and Bacteria

include prokaryotes which are organisms who lack membrane-bound organelles and a nucleus.

binomial nomenclature

a naming system in which each individual is given a two-part name, such as genus and species or first name and surname

r/K selection

a form of mathematical classification based on the number of offspring a species produces and the level of parental involvement required to care for them.

R selected

unstable environment, small in size, energy used to make individuals is low, early maturity, short life expectancy, each individual reproduces once. (e.g. butterflies)

K selected

stable environment, large size of organisms, energy used to make individuals is high, less offspring are produced, late maturity, long life expectancy, individuals reproduce more than once. (e.g. humans)

parthogenesis

a female's egg develops into a new organism without ever having to be fertilised by a sperm cell (genetic replica of parent)

budding

an offspring grows right out of the body of the parent (like a bud - most common are coral polyps)

fragmentation

parent breaks into multiple pieces and each develops into an independent being

fission

the parent organism is replaced by two daughter organisms, because it literally divides in two.

pros and cons of asexual reproduction

Positives: less energy and resources required, faster process, one source of genetic material

Limitations: cannot adapt to environment (as they have the same genetic material as parent) - unless there is a mutation

sexual reproduction

combination of genetic material from two individuals to produce a new combination of genes.

positives and negatives or sexual reproduction

Positives: genetic mix so there is a greater range of genetic material

Negatives: slower process, more energy and resources, partner needed

what sequences of molecules are used to classify organisms

DNA and proteins as they are inherited from ancestors -> more information about shared ancestors

what do the order of the bases (A,T,C,G) determine

the physical and physiological features of an organism.

what contributes to individuality (relating to bases)

the order in these bases (A,T,C,G)

how can amino acids be used for classification

the order of amino acids (within proteins) can be used for classification

phylogenetic trees

Branching diagrams that depict evolutionary relationships.

extant

still existing; not exterminated, destroyed, or lost

how are phylogenetic trees organised

organised vertically and are generally oriented with the bottom of the tree representing a time in the past and the top representing the extant species.

clade

A group of species that includes an ancestral species and all its descendants.

cladograms

a phylogenetic tree in which all organisms are grouped according to their most likely evolutionary relationships.

cladistics

a taxonomic technique that arranges organisms by clade

what does cladistics rely on

1. Because all life evolved from a single ancestor, any group of organisms will share a common ancestor at some point in the past

2. The offspring of an ancestral species diverge dichotomously in a process called cladogenesis

3. Organisms become increasingly different as they continue evolving from their point of cladogenesis

what does the second assumption of cladistics suggest

· all speciation events (new species develops) are singular splits

· the new generation of a particular organism will either be the same as their parent generation (plesiomorphic) or different in one way (apomorphic)

what does the split between clades represent

with a V-shape with the point of the V (node) representing the last ancestor the clade in common.

how is the difference in each organism noted

by an apomorphic feature "changed character" (different physiological makeup that a common ancestor had)

what is the structure of a cladogram

- A root is the beginning of an organism's ancestral lineage.

- A node is a point of branching from a common ancestor.

- A branch (or internode) connects two nodes.

- A leaf refers to an individual species.

molecular homology

the identification of shared biomolecular elements - generally genes - used to test the relationships between organisms which can demonstrate common ancestry.

comparative genomics

the study of DNA similarities across species to further our understanding of their relatedness.

conserved sequence

a DNA or protein sequence that is preserved across species due to optimal function.

how is a protein subjected to natural selection

A protein that is well suited to its function will be conserved through time, while other traits around it may evolve.

what must happen to DNA to be expressed

A section of DNA must be unwrapped from its histone for the enzymes involved in replication and expression to gain access to it

what can mutations in the histone proteins do to DNA

Mutations in the histone proteins can cause the DNA to bind only loosely, not at all or to bind so tightly that the mechanisms for unwrapping the DNA fail to be effective

what happens if mutations change the structure or function of proteins

If mutations change the structure or function of the proteins that are encoded, they will change the way those proteins are passed to the next generation, making them either more or less common in subsequent generations.

mutation rate

the estimated number of base pair changes per nucleotide site per generation of a population.

neutral mutation

mutation of little consequence to survival and reproduction

what does the comparison of genome sequences allow

making it possible to trace evolutionary processes responsible for the divergence of two genomes.

molecular phylogeny

the study of evolutionary relationships using comparative genomics.

biological species concept

a species is a group of organisms who can interbreed within natural populations which are reproductively isolated (ie - mating between organisms of different species can't produce offspring, mating produces infertile (unable to reproduce) or non-viable (able to survive) offspring).

what are limitations of the biological species concept

- cannot be applied to organisms that reproduce asexually, or reproductive data is unavailable

- only considers species at a certain point in time and ignores evolutionary/ecological processes that shaped the reproductive isolation between groups

phylogenetic species concept

a species is a group of organisms that share a pattern of ancestry and descent that can be genetically mapped, and which form a single branch on the tree of life.

what are the limitations of the phylogenetic species concept

Cannot be applied to organisms that are long-extinct

morphological species concept

a species is a group of organisms which appear identical by morphological criteria (anatomical or physical characteristics).

when is the morphological species concept applied

This method is used when other methods are not possible where there is limited or unavailable data on reproductive behaviour or genetic similarity, eg - an extinct organism found as a fossil where no biochemical samples are possible

what are the limitations of the morphological species concept

Morphology can be mis-leading - many organisms have similar characteristics in body shape and colouration due to an evolutionary adaptation to a similar living environment