Untitled Flashcards Set

Evolution Quiz 

Biological evolution:

• The scientific theory that states that living things have diverged from the same ancestors 

• The idea that the universe has a history and that change over time has taken place

Development:

• Physical changes that occur during an individual’s life, resulting from growth or the natural aging process

  • Cosmetic alterations and scars are non-inheritable traits 

Adaptations: the process by which organisms develop traits that enhance their survival and reproduction in a specific environment, leading to changes in populations over time

• Structural adaptations: physical features (fish scales, insect camouflage, birds’ hollow bones)

• Physiological adaptations: internal body processes or functions (skunks and their spraying liquid, wood frogs and cryoprotection, axolotl and their brain/spinal cord/heart tissue regeneration, cuttlefish and camouflage using specialized cells)

• Behavioral adaptations: innate or learned

  • Innate: migration, hibernation, mating rituals, penguins huddling for warmth/safety

  • Learned: crows and tools, lions huddling in prides, pack hunting strategies 

Mutations = The Source of Genetic Variation

• create new genes that provide a continual supply of new genetic information

mutations in population - immediate and direct effect on individuals as well as potential

to influence future generations when those mutations are inherited

Mutations must occur in the germ line (gametes) to be passed on

• Neutral mutation: mutation that doesn’t result in any selective advantage or disadvantage 

• Harmful mutation: any mutation that reduces the reproductive success of an individual and is therefore selected against, do not accumulate over time 

• Beneficial mutation: any mutation that increases the reproductive success of an individual. These are favoured by natural selection and do accumulate over time. 

Evolutionary adaptation: when a mutation is favoured by the environment

• Mutations produce heritable changes in individuals called derived traits 

• Harmful = no pollination, discontinued quick

• Neutral = infrequent pollination, lasts but irregular

• Favourable = lots of pollination, passed through generations

Selective breeding: when artificial selection is used to create an ideal offspring 

• Domestication: provides us with food supply

Similarities:

• Cannot change/alter the phenotype s of the organism during its lifetime

• Can only change/alter the phenotypes of the offspring yet to be born by manipulating the parental genotypes

• Required time to achieve offsprings with desired traits

• Can varies gene pool within a species population

• Can lead to the formation of a new species

Fossils: ancient remains, impressions or traces of an organism or its activity that have been preserved in rocks or other mineral deposits in Earth's crust 

• Bodies fall in sediments (no oxygen) and mineralize over time 

•  minimum 10 000 years old 

• hard body organisms - shell, bones, teeth more likely than soft bodied 

• dinosaur - well known but very rare compared to marine 

• footprints, burrows and fecal remains too 

• organisms trapped in amber (fossilized tree sap), volcanic ash, ice formations (permafrost, acidic bogs

catastrophism: the theory that catastrophes such as floods, diseases and droughts periodically destroy species (extinction) living in a particular region – allowing species from neighbouring regions to repopulate the area 

• Flaw: layers in strata suggest species becoming more complex

Greeks 

• Believed that things originated from water or air 

Aristotle

• Believed that living things are immutable 

• Created “Scala Naturae“ = “Great Chain of Being” 

15-18 century

• Philosopher realized the importance of careful observations, experimentation and deductive reasoning

Medieval times

• Theory of creationism: everything was created and does not change 

• believed in Spontaneous generation = all things originate from inorganic matter

• Observed frogs coming from slime

• Maggots from matter

= Prevented genetic thinking, speculation about evolution and descent with modification

Francesco Redi (1629 -1697)

• Disproved spontaneous generation: showed that Maggots come from fly eggs not randomly from rotting meat

Carolus Linnaeus (1707-1778)

• Father of modern taxonomy

• At first believed immutability but observed hybridization experiments in plants where new species formed so reformed his beliefs and influenced others 

• BUT…maintained that the transformations were divine

Comte Georges-Louis Leclerc De Buffon (1707 – 1788)

• Naturalist

• Wrote 44 page “Histoire Naturelle” – understanding of the natural world 

• examined animal anatomy - found those which serve no purpose (pigs extra toe that doesn't reach ground)

• Considered similarities between apes and humans  

• Believed species changed over time 

• Speculation because no explanation (mechanism) to account for it 

Georges Cuvier (1769-1832)

• Father of paleontology

• Each stratum (layer) has unique group of fossils (strata above different from below) 

• Deeper layers are older (back in time) than surface layers which are newer 

• More complex species (resembling modern species) are found in the younger, shallower layers 

• Simple species (bacteria, algae, jellyfish) are found in all strata 

• New species appear and others disappear over time – evidence 

• Cuvier didn’t believe species change – just replaced = catastrophism 

Charles Lyell (1797-1875)

• Rejected catastrophism – proposed uniformitarianism

• Reasoning – if geological changes are slow and continuous then the Earth must be more than 6000 years old

• Theorized slow, subtle processes over a long period of time could result in substantial changes (i.e. mountain formation)

• Inspired darwin 

Thomas Malthus (1766-1834)

• Theory of population growth inspired Darwin’s theory of natural selection

• Populations produce many more offspring than can survive on the limited resources available

• Poverty, famine, disease are natural outcomes that result from overpopulation

• BUT believed divine forces were ultimately responsible and designed by God 

Lamarck (1744-1829)

• proposed evolutionary change resulted from two distinct principles

  • 1st principle - use and disuse: structure that are used more often become larger and stronger while those not used become smaller and weaker 

  • 2nd principle - the inheritance of acquired characteristics: individuals could pass on to their offspring characteristics they had acquired during their lifetime ex. If a giraffe stretched its neck over its lifetime then the offspring would be born with slightly longer necks 

--> explained how species adapted to environment and how they might evolve if the environment changed (cooler climate --> thicker coat --> pass on to offspring --> better adapted)

==> FLAWED because although characteristics may be acquired, many features do not change in response to use --> features that change are not normally heritable

• Many features – do not just such as vision 

Significant contributions --> discussions: 

• All species evolve over time

• All species evolve in response to environment and become better adapted to it

• Changes are passed on from generation to generation 

Catastrophism and uniformitarianism both shape the land but according to the evolution theory based on catastrophism is FALSE. 

IF SEEN ON TEST

GEOLOGICALLY = BOTH ARE RIGHT

BIOLOGICALLY = UNIFORMITARIANISM

Evolution Quiz 2

Galapagos Island:

• 1000 km west coast of South America 

• Had no amphibians  because they die in salt water or large land mammals because they can’t survive without fresh water

  • Only species that arrived by water or air lived there (insects, birds, plants, reptiles) FINCHES FOUND HERE 

Charles Darwin 

• Started discovering his hypothesis after 1836, originally believed species were immutable 

• Collected fossils, plants, animals and made observations

  • Noticed that modern and extinct animals that resemble each other seemed to share similar geographic distributions 

• Found evidence that the earth was dynamic and changing after an earthquake where coast risen 3m out of water

• hypothesized that remote oceanic islands became populated by species that arrive by air or by water and as they established = evolved into new species over time

• Darwin’s finches evolved to have different shaped beaks to adapt to different food sources 

• Theory of descent with modification = how species change over time, giving rise to new species, and share a common ancestor, with modifications occurring through natural selection and inheritance

Evidence of Evolution 

1. Fossil record 

• Strata closest to the surface = more modern 

• Fish are the oldest vertebrates → amphibians → reptiles → mammals → birds

2. Biogeography 

•  scientific study of the geographic distribution of organisms based on both living species and fossils

• Isolated islands have unique species found no where else but they resemble the mainland species rather than similar

• They face similar selective pressures = evolve to have similar traits 

3. Comparative anatomy

• Homologous features: a structure with a common evolutionary origin that may serve different functions in modern species = the species share a common ancestor 

• Analogous features: a structure that has the same function but doesn’t have the same structure. These species with analogous features do not share a common ancestor but have evolved in similar ways due to environmental pressures 

• Vestigial features: non-functioning or only marginally functioning structures that is similar to a fully functioning structure in another species aka a part of the body that is not used much anymore 

  • Ex. wisdom teeth, goosebumps

Ex. Recurrent laryngeal nerve-vertebrates

Fish - nerve exits brain and follows short direct path to gill close to heart

Mammals - nerve exits brain but follows indirect path (heart -->back up neck and enters larynx/voice box)

Giraffes - nerve exits brain, travels full length of neck, down to heart and back again before entering larynx (distance from brain to larynx is few cm but nerve travels more than 4m)

4. Embryology 

• Development processes and patterns 

• Fish, chickens and humans have similar traits as embryos but develop differently

5. DNA Sequencing (after Darwin)

• All living organisms share the same genetic code because we all come from a common ancestor

• DNA sequences between species show how closely related they are, the closer you are related to each other = less genetic differences

Competition between populations

• Thomas Malthus - Principle of Population (1838) - all populations were limited in size by their environment - and in particular their food supply (could not grow indefinitely)

• Darwin theorized that the environment favours survival of certain individuals

Natural selection: how the environment favours the reproductive success of a individuals within a population over others 

• Variation: organisms within a population are different from each other

• Inheritance: The instructions for inheritance of different traits are passed on from parent to offspring

• Selection: organisms with different traits (positive) are selected for reproduction

Adaptation: the ability to change to match the conditions in your environment and to increase your reproductive success

Mechanisms of Evolution

1. Natural selection 

• Genetic variation = by chance through genetic mutations and recombinations 

• Natural selection is NOT by chance = the environment favours certain traits over others

2. Sexual selection

• Differential reproductive success caused by

  • Ability obtain mates 

  • Results in sexual dimorphism 

  • Mating and courtship behaviours

• Occurs through female choice and male-male competition 

• Females choose based on physical traits

• males evolved larger body size and physical attributes like antlers for competition – fight to establish control over territory where females are to mate

3. Genetic drift

• Changes to allele frequency due to chance, more obvious in small populations

• Can make alleles very common or make them disappear entirely over generations

Bottleneck drift:

• Dramatic, often temporary reduction in population size, usually resulting in significant genetic drift

  • Loss of genetic diversity = species more vulnerable to disease

Founder effect:

• When a small number of individuals separate from their original population and form a new population

• Common alleles may not be so common anymore or rare alleles may become common

4. Gene flow (aka migration)

• The transfer of alleles from one population to another

• Happens when individuals from different populations of the same species interbreed

• Adds to genetic diversity because new traits are intermingling 

• Can also reduce genetic diversity because over time if they keep mating together, they will all have similar traits and will become more similar to the original population

5. Mutations 

• Changes in DNA sequence of an organism’s genome

• Naturally occurring due to errors in DNA replication or environmental factors (ex. radiation)

• Can be beneficial, neutral or harmful

• Mutations can accumulate over time becoming evolutionary changes

6. Artificial selection

• Humans selecting what traits get passed on to breed for desired plants/animals 

Hardy-Weinberg Principle - the following conditions result in evolution

1. Natural selection: favours the passing of some alleles over others

2. Mutation: introduces new alleles to a population

3. Immigration or immigration: introduces or removes alleles in a population

4. Horizontal gene transfer: the gaining of new alleles from different species 

5. Small population: increases likelihood of genetic drift

Adaptive radiation is the rapid evolution of diverse species from a common ancestor, usually when they colonize new environments with different ecological niches. This leads to species adapting to various conditions and roles.

Example:

• Darwin's finches on the Galápagos Islands evolved into different species with distinct beak shapes to exploit different food sources.

Evolution Unit Test

Everything above +

7. Speciation

• Microevolution: small changes in gene frequencies and phenotypic ratios within a population

• Macroevolution: large-scale changes like the formation of a new species which occur over a long period of time (centuries, millenia)

Speciation: formation of a new species 

What is a species? - idea created by Ernst Mayr? 

• A group of organisms that can interbreed and produce fertile offspring, and are reproductively isolated from other groups 

• Can be identified by morphology/appearance and genetic makeup

Modes of speciation

• Species need genetically unique features that isolate them from others genetically and reproductively

Mechanisms of speciation

• reproductive isolation mechanism: any behavioral, structural or biochemical trait that prevents two species that live in the same region from successfully reproducing with each other

Allopatric speciation: formation of a new species due to evolutionary changes that occurred during geographic isolation

• Can no longer share genetic information bc the mutations that occurred in isolation were not shared, the difference in environment made the new species adapt/ genetic drift

• Will probably develop its own unique reproductive isolation mechanisms

Sympatric speciation: evolution of populations into separate species within the same geographic region

• Can occur gradually or suddenly

• Disruptive selection may have occurred (two different extremes of a trait)

• Small amount of inbreeding 

Patterns of evolution:

• Divergent evolution: species that were once similar to an ancestral species become increasingly distinct

• Convergent evolution: similar traits arise because species adapted independently of each other due to environmental conditions

• Coevolution: one species evolves in response to the evolution of another species 

8. Macroevolution

Large scale changes over a long period of time leading to formation of new species and new taxa

Abiogenesis - origin of life from non-living matter 

• Cambrian Explosion – rapid evolution of most major animal phyla that took place over approximately 40 million years during Cambrian period (Palaeozoic era) – 542 million years ago began and 251 mya cataclysmic event – 90% of known marine species wiped out

• 60 million years ago: mass extinction event (Yucatan peninsula crater due to meteorite impact)= birds are the only surviving descendants

Phylogenies: (classification of species) based on careful evaluation of wide range of evidence including fossil record, genetics and morphology

Cladograms: visual representation of evolutionary relationships 

Cladistics: method of determining evolutionary relationships based on presence or absence of recently evolved traits 

Derived traits: trait that has evolved recently due to adaptations

Synapomorphy: derived trait shared by 2 or more species/groups making them more closely related

Sample cladogram: 

Gradualism and punctuated equilibrium:

• Pace of evolution; how quickly to evolve from one to another and adapt to changes in environment

• Climate change and humans impact pace of evolution

Both are accepted as true - 

if environmental changes are slow = evolutionary changes would be gradually 

if species exposed to new or rapidly changing environmental conditions = we can expect a rapid evolution

Ex. after mass extinction, species enter new environment with far fewer competitors

Gaps and missing links 

• Theory of gradualism and punctuated equilibrium is still valid w/o all the evidence

Gaps because?

• species with delicate bodies don’t fossilize easily 

• environment may not have conditions for it

Transitional forms: fossils or species that are intermediate in form between 2 other species in a direct line of descent AKA direct line 

• Archaeopteryx fossil – first and most famous transitional species (features of both birds and primitive reptiles – bony jaw with teeth, long bony tail but also feathered wings)