BIO SL 5.1,5.2,5.3,5.4

evidence for evolution: 5 main concepts

-fossil record

-selective breeding

-adaptive radiation/comparative anatomy

-patterns of variation

-DNA/neo-darwinism

Outline the types of evidence that can be used to support the theory of evolution. (4)

a. fossils (give evidence of evolution);

b. fossils show different species existed in the past/species changed over time;

c. selective breeding of (domesticated) animals/crop plants;

d. selective breeding shows that (artificial) selection can cause rapid change;

e. homologous (anatomical) structures/vestigial organs (give evidence of evolution);

f. homologous structures/pentadactyl limbs/other example show common ancestry;

g. DNA/base/amino acid sequences show (common) ancestry/species diverged;

Do not award marks for examples of evolution in response to environmental change such as melanism as this is tested in part (c) of this question.

definition of evolution

cumulative change in heritable characteristics of a population between generations

requirements of evolution

-variation within a species (genetic and environmental)

-selection pressures (act on individuals because of variation)

fossil record

-->the totality of fossils: discovered and undiscovered

petrified remains/traces of animals

provides features of ancestors to compare against living descendants

carbon dating of fossils = essential

sequence of fossils matches evolutionary theory

law of fossil succession

consistent order of organisms presence in the fossil record

eg. prokaryotes before eukaryotes; ferns before flowering plants

incompleteness of fossil record

importance in recognizing incompleteness of fossil record

fossils require specific conditions

only fragments of remains discovered

missing links because of limited fossil data

transitional fossils

show intermediary forms of the evolutionary pathway of a single genus

establish links between species and ancestors/predicted descendents

Outline how fossil records can provide evidence for evolution. (2)

a. the sequence in which fossils appear matches the expected sequence of evolution;

b. comparisons with fossils and living organisms (morphology) shows change in characteristics from an ancestral form / OWTTE;

Vestigial organs and homologous structures are acceptable answers.

c. fossils of extinct species show that (evolutionary) change has occurred;

d. fossils can be dated with radioisotopes / geological depth/strata indicates (relative) age/date of organism;

e. can yield DNA for molecular clock analysis;

f. example of any of the above can earn one mark (eg: reptiles follow amphibians);

selective breeding definition

a form of artificial selection

process by which certain domesticated species get altered by choosing individuals based on characteristics

selective breeding as evidence for evolution

targeted breeds show significant variation in relatively short period

selective breeding examples

plants crops: bred to produce different foods

-broccoli: modified flower buds

-cabbage: modified leaf buds

-kale: modified leaves

domesticated animals: diverse breeds of offspring

-dogs: targeted selection of particular traits; from wolf ancestor; hunting/herding/racing/toy

-horses: race horses versus draft horses

-cows: improved milk production; increased muscle mass (belgian blue)

comparative anatomy

evolution of homologous structures by adaptive radiation - similarities in function while difference in appearance

-> implies common ancestry

adaptive radiation

several new species rapidly diversify from single ancestral source; each new species adapts to utilize unoccupied niche

leads to homologous structures

homologous structures

same basic structure while difference use/function

illustrate adaptive radiation

examples of homologous species

copmparison of pentadactyl limbs in mammals, birds, amphibians, & reptiles although locomotion differs

convergent evolution

independent evolution towards similar features by species in different lineages

leads to analogous species

not closely related but adapt to same niche

analogous structures

common function, different structure

- represent adapting towards same niche without common ancestor

speciation

--populations of a species gradually become their own species

formal definition: continuous variation across geographical range leads related populations to gradually diverge

depedent on genetic variation - continuous; gradual and cumulative rate of change

- geographical separation leads to speciation

variation patterns

continuous variation across geographical range of related populations --> supports gradual divergence/speciation

-what happens over space relates to what happens over time

theory of evolution

charles darwin; alfred russell wallace

-all organisms shared common ancestor

-evolution is drived by natural selection

natural selection

survival of the fittest -- the ones most responsive to change

fundamentals of theory of evolution (natural selection necessities)

1-heritable variation amongst members of the same species

2-overpopulation of offspring: intraspecies competition

3-adaptations: characteristics that make indv more suited to environment

4-selection: environmental pressures lead to differential reproduction

5-progressive change-->natural selection

natural selection mnemonic

ICE AGE

inherited variation

competition

environmental pressures

adaptations

genotype freq

evolution

forces of variation

mutations - changing genetic composition of gametes, forms new alleles

meiosis - either crossing over or independent assortment

sexual reproduction - combination of genetic material from 2 distinct sources creates new gene combinations

Explain how sexual reproduction promotes variation in a species. (3)

sexual reproduction involves interbreeding/genetic material from two parents;

new combinations of paternal and maternal chromosomes/alleles/genes / (random) fertilization;

which leads to new genetic combinations/greater variation;

meiosis creates a great variety of gametes;

by crossing-over / by random orientation of alleles (during meiosis);

Explain how sexual reproduction can eventually lead to evolution in offspring. (8)

offspring vary in traits;

variation results from sexual reproduction;

independent assortment of alleles (during meiosis of spermatogenesis/ oogenesis) contributes to variation;

meiosis is the cellular process that produces gametes;

crossing over (during meiosis) increases variation;

fertilization (combination of different genomes) contributes to variation;

more offspring may be produced than the environment can hold;

struggle for existence can occur;

offspring whose traits best adapt them to environment will survive/survival of fittest;

change in environment will lead to survivors with new/different traits;

correct use of term natural selection/selective pressure;

variation is heritable / over time more offspring born with new trait;

change in gene pool;

when entire population (of a species) exhibits new trait, evolution has occurred;

malthusian dilemma

populations multiply geometrically while food resources increase arithmetically

- environment can't support population growth

leads to competition

types of adaptations

structural - phyical differences

behavioral - patterns of behavior

physiological - detection and response by vital organs

biochemical - molecular composition of cells/enzymes

developmental - variable changes across the life span

alleles & frequency

encode phenotypic polymorphisms of a particular

beneficial, detrimental or neutral (determined based on environmental conditions)

proportion of different alleles changes across generations due to natural selection & evolution

case study: Peppered Moths (biston betularia)

exemplifies natural selection

2 distinct polymorphic forms: light colouration, darker melanic variant

-unpolluted environment: trees have pale-colored lichen, provides camouflage for lighter moth

-polluted environment: sulphur dioxide kills lichen, soot blackens the bark - provides camouflage for darker moth

-->pollution/environment directly effects presence of moths

- pre-industrial rev, post-industrial rev, european environmental policies

case sudy: daphne major changes in beaks of finches

example of adaptive radiation

-rapid evolutions diversification

variety of niches, impacted by geographical location/different islands

finches beaks change based on diet

occured on daphne major

compact/powerful beaks are to eat seeds--large ones = better; extended drought in 1977 made seed cases tougher, larger beaks allele frequency increased

Describe how natural selection leads to evolution. (6)

populations produce more offspring than can survive;

individuals show variation;

limited resources;

create a struggle for survival/competition;

survival of the fittest / some are better suited to the environment and survive;

variation/characteristic must be heritable;

best fitted individuals survive to reproduce;

advantageous variation/characteristic/allele passed on;

over time advantageous variation/characteristic/allele increases in the population;

case study: antibiotic resistance

example of evolution

antibiotics = chemicals produced by microbes

commonly used by man to combat bacterial diseases

resistant bacteria will survive and reproduce, flourish without other bacteria present

example: golden staph - staphylococcus aureus

causes infection to skin, or more serious infections

resistant to antibiotic methicillin

--plasmid transfer allows interspecies transfer

Explain how evolution may happen in response to an environmental change. (8)

a. (genetic) variation in population;

b. (variation is) due to mutation / sexual reproduction;

c. valid example of variation in a specific population;

d. more offspring are produced than can survive / populations over-populate;

e. competition / struggle for resources/survival;

f. example of competition/struggle for resources;

g. survival of fittest/best adapted (to the changed environment)/those with beneficial adaptations / converse;

h. example of changed environment and adaptation to it;

i. favourable genes/alleles passed on / best adapted reproduce (more) / converse;

j. example of reproduction of individuals better adapted to changed environment;

k. alleles for adaptations to the changed environment increase in the population;

l. example of genes/alleles for adaptations increasing in a population;

m. evolution by natural selection;

n. evolution is (cumulative) change in population/species over time / change in allele frequency;

Explain two examples of evolution in response to an environmental change. (8)

For each example:

a. a named example of a species that has evolved in this way;

b. description/clear statement of the change that occurred in the environment;

c. description/clear statement of different varieties (that existed at the same time);

d. explanation of/reason for one variant having a selective advantage;

e. the change in the population/species due to natural selection/evolution;

Do not award the last mark if the change is explained using Lamarckism rather than natural selection.

Example:

f. Staphylococcus aureus/MRSA/Clostridium difficile/other named species;

g. introduction/use of an antibiotic/named antibiotic;

h. some bacteria were resistant and others were not;

i. resistant bacteria survived (and multiplied) while non-resistant were killed;

j. percentage of the population showing resistance increased;

[8] can be awarded if the candidate scores [5] for one example and [3] for the other.

Do not accept examples where the evidence of evolution comes from fossils, or where the variation is not heritable.

binomial nomenclature

formal system of naming and classifying species; taxonomy

shows how closely species are related, identification/comparison of organisms

--> first name: genus(capitalized), follows by species (lower case)

italicized, in HANDWRITING: UNDERLINE

Outline the use of the binomial system of nomenclature in Campanula persicifolia. (2)

a. first name/Campanula for genus / second name/persicifolia for species;

b. (all) members of Campanula persicifolia share special/unique features;

c. two names make a unique combination to designate species / worldwide recognized nomenclature;

Taxonomists aim to place species into genera, families and higher taxa according to their evolutionary origins. This is known as natural classification.

Explain the usefulness of natural classification in biodiversity research. (2)

a. «because» it allows easier identification of a species

b. «because» it can help identify common ancestors/evolutionary paths/close relationships (showing degree of biodiversity) / OWTTE

c. «because» it is universal/cross-cultural language that avoids problems of local names of organisms

OR

«because» it promotes international collaboration

OR

«because» it facilitates access to the history/background of the species /indexing for retrieval of relevant «taxonomic» information / OWTTE

d. «because» it allows «biodiversity» research of larger taxa «ie examination of a family of large cats rather than one species»

domains of life

eukarya - eukaryotic organisms

archaea - prokaryotic cells, extremophiles

eubacteria - prokaryotic cells, common pathogenic forms

hierarchy of taxa and mnemonic

(Dear)KingPhilipCameOverForGrapeSoda

Domain

Kingdom

Phylum

Class

Order

Genus

Species

EX: classification of one animal (humans)

D: eukarya

K: animalia

P: chordata

C: mammalia

O: primate

F: hominidae

G: homo

S: sapiens

EX: classification of one plant (wild rose)

D: eukarya

K: plantae

P: angiosperms

C: rosids

O: rosales

F: rosaceae

G: rosa

S: rosa acicularis

Living organisms have been placed in three domains: archaea, eubacteria and eukaryote. Distinguish archaea from eubacteria. (3)

artificial classification

arbitrarily selecting unifying characteristics, then grouping organisms

easy to develop; does not show evolutionary relationships

natural classification

grouping organisms based on similarities first, then identifying shared characteristics

all members would have shared ancestor

used to predict characteristics; highly mutable, changes with new information

phylogenetic classification

classification based on assumed evolutionary ancestry, creates cladograms and uses DNA to assess relatedness

example of con to natural classification: reclassification of hominids

kingdoms

plantae, animale, fungi, protista

archaebacteria

eubacteria

phlyum of the plantae kingdom

bryophyta

filicophyta

coniferophyta

angiospermophyta

bryophyta

MOSS

no roots, vascular system, woody stem, leaves, seeds, fruit

anchored by rhizoid

reproduce by releasing spores

bryophyta example

silvery bryum

Bryum argenteum

filicinophyta

FERNS

has roots, vascular system, leaves

no seeds or fruit

pinnate leaves

reproduce by releasing spores

filicinophyta example

royal fern

osmunda regalis

coniferophyta

PINE/CONIFERS

has roots, vascular, woody stem, leaves, and seeds

needle leaves

reproduce by non-motile gametes (seeds) found in cones

coniferophyta example

ponderosa pine

pinus ponderosa

angiospermophyta

FLOWERING PLANTS/GRASS

has roots, vascular, leaves, pollen, seeds, and fruit

broad leaves

highly variable

reproduce by seeds in ovules within flowers

angiospermophyta example

wild rose

rosa acicularis

plant phyla recognition table

Plants are a diverse group of eukaryotic organisms. Describe the different characteristics of the bryophyta, filicinophyta, coniferophyta and angiospermophyta.

(At least one characteristic from each group is needed for maximum credit.)

bryophyta have no roots / only have rhizoids;

bryophyta have simple leaves/stems / only a thallus;

bryophyta produce spores in capsule;

byrophyta are nonvascular;

bryophyte exhibit (pronounced) alternation of generations / a significant gametophyte generation;

filicinophyta have roots, stems and leaves;

filicinophyta (often) have divided/pinnate leaves;

filicinophyta produce spores in sporangia/spores on the undersides of leaves;

filicinophyta exhibit alternation of generations;

filicinophyta have primitive vascular tissue / no true xylem and phloem;

coniferophyta have woody stems;

coniferophyta (often) have narrow leaves/needles/scales;

coniferophyta produce seeds in cones/unenclosed seeds;

angiospermophyta have flowers;

angiospermophyta have ovules in ovaries;

angiospermophyta produce seeds (with hard coats) in fruits;

Using simple external recognition features, distinguish between the plant phyla bryophyta and angiospermophyta. (4)

nonvascular; vascular

small / 7 cm; tall / up to 100 m

reproductive structures / capsules appear on stalks; have flowers

microscopic spores; covered seeds / fruits

rhizoids; roots

phylum of animalia kingdom

porifera

cnidaria

platyhelmintha

annelida

mollusca

arthropoda

chordata

porifera

SPONGES

live in water

sessile - attached to rocks

porous

filter feeder

no symmetry, segmentation, mouth/anus, muscle/nerves, organs,

porifera example

spongilla lacustris

cnidaria

JELLYFISH, CORAL, SEA ANEMONE

sessile/free swimming or both

radial symmetry

feed: sting with nematocysts, trap with tentacles

mouth

no anus, skeleton, segmentation

cnidaria example

moon jelly

aurelia aurita

platylhelminthes

FLATWORMS

bilateral symmetry

flattened body

mouth

one body cavity

no anus, segmentation, heart/lungs/organs

platyhelminthes example

girardia tigrina

annelida

SEGMENTED WORMS

water or soil

bilateral symmetry

visible segmentation

bristles

gastric tract - mouth on one end, anus on another

annelida example

capitella capitata

mollusca

SNAILS CLAMS SQUIDS OCTOPUS

mostly aquatic

bilateral symmetry

CaCO2 shell

mouth and anus

no segmentation

mollusca example

mimic octopus

thaumoctopus mimicus

arthropoda

CRUSTACEANS, INSECTS, SPIDERS

largest animal phylum

aquatic/terrestrial

bilateral symmetry

chitin exoskeleton

segmentation

mouth and anus

jointed limbs

arthropoda example

roly poly

armidillidium vulgare

invertebrate phyla recognition table

chordata common characteristics

- notochord: line of cartilage along back that provides support (at some point in development)

-not all vertebrates, but most have bony backbone

-dorsal nerve cord: bundle of nerve fibers connecting brain to muscle/fibers

-hollow dorsal neural tube

-post-anal tail

pharyngeal slits: openings connecting inside of throat to outside

vertebrate characteristics

dorsal neural tube develops into spine

notochord forms pretective backbone

vertebrate classes

birds (aves)

amphibia

mammalia

reptilia

fish (agnatha, chondrichthyes, osteichthyes)

fish

fins

gills

external fertilization

live in water

jelly covered eggs

bony scales

exothermic (cold blooded)

fish example

common carp

cyprinus carpio

amphibian

4 pentadactyl limbs

lungs: simple, moist skin

external fertilization

larval stages in water

jelly covered eggs

permeable skin

exothermic

amphibian example

common toad

bufo bufo

reptiles

4 pentadactyl limbs

lungs: extensive folding

internal fertilization

soft shell eggs

chitin scales

exothermic

non-living teeth

reptile example

loggerhead sea turtle

caretta caretta

birds (aves)

4 pentadactyl limbs

lungs: peribronchial tubes

internal fertilization

hard shell eggs

feathers

endothermic

beak

birds example

snowy owl

bubo scandiacus

mammals

4 pentadactyl limbs

lungs: w/ alveoli

internal fertilization

live birth

produce milk

hair

endothermic

living teeth

mammals example

human

homo sapien sapien

dichotomous key

method of identification

groups of organisms are repeatedly divided into two

identifies specimens by immutable features (do not change; visible)

vertebrate classes recognition table

clade definition

a group of organisms that have evolved from a common ancestor

cladograms

tree diagrams that show the most probable sequence of divergence in clades

represent evolutionary history/phylogeny of the clade

node

represents common ancestor and speciation event

human cladogram example

key features of a cladogram

root: initial ancestor common to all demonstrated organisms

nodes: hypothetical common ancestor

outgroup: most distantly related species in cladogram, point of comparison/reference

clades: common ancestor and all of its descendants

cladograms are based on..

morphological (structural) features or molecular evidence

using structural evidence

1 - organize selected organisms and defined characteristics (developmentally fixed characteristics)

2 - venn diagram/linear cladogram

-->closely related species expected to show similar structural features, now proven wrong because of adaptive radiation and convergent evolution

using molecular evidence

1 - select gene/protein common to range of selected organisms

2 - copy the molecular sequence for each

3 - run multiple alignment to compare molecular sequences

4 - generate a cladogram from multiple alignment data

--> the more similar the base sequences, the more closely related

--> gradual accumulation of sequence differences supports evolutionary claims

List two types of evidence used to determine which species belong in the same clade. (2)

a. DNA/base sequences (of a gene/genes)

b. amino acid sequences (in a protein/proteins)

Do not credit references to morphology.

In which domain are bryophyta found?

A. Plantae

B. Archaea

C. Eubacteria

D. Eukaryote

D