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Question 1

How does evolution occur?

Answer 1

By natural selection, relationship between organisms and environment is core, relationship is fundamentally a evolutionary one, organisms are not adapted to environment but happen to be suited to it due to selection on their ancestors, evolution through natural selection.

Question 2

How are organisms moulded by past environments?

Answer 2

By natural selection, variation in heritable traits contributed to fitness, better suited traits tend to lead to higher fitness and more descendents. Selection towards fittest given available variation and constraints.

Question 3

What is specialisation between species called?

Answer 3

Ecotypes, fingerprint of natural selection can be seen within species, NS can favour different, locally specialised variants where populations experience different environments and are relatively isolated. Ecotypes are genetically determined differences between populations that reflect local matches between organisms and their environment.

Question 4

What is a plant example of Ecotypes?

Answer 4

Sapphire rockcress arabis fecunda. High (wetter) and low (drier) elevation pops. Local adaptation has implications for conservation.

Question 5

What can Ecotype adaptation sometimes be?

Answer 5

Not local, e.g. partridge pea. Grown at home site or transplanted from distances up to 200km away. Very few differences in characters, only difference was found between farthest sites. Hybridisation (gene flow) can outweigh local adaptation across all but largest scales.

Question 6

Specialisation within species - what is genetic polymorphism?

Answer 6

There can also be distinct heritable trait differences within pops due to heterozygotes of superior fitness. Gradient of selective forces : differences at end, mixes in the middle. Frequency- dependent selection e.g. rare morph not recognised by predator.

Question 7

What is an example of anthropogenic selection pressures?

Answer 7

Industrial melanism in peppered moth. Pollution from coal burning - blackens surface and loss of moss and lichen. Predators selected against light form on darker surfaces. Darker in cities and to west of cities, went back to light again once coal reduced. Transient change within.

Question 8

What is the definition of species?

Answer 8

Group of organisms usually with distinctive heritable traits held together by force of cohesion. Under the biological species concept, generation of viable offspring through sexual reproduction ensure genetic mixing and cohesion.

Question 9

What is ecological speciation?

Answer 9

From different selection regimes in distinct subpopulations

Question 10

What is allopatric speciation?

Answer 10

When secondary contact never occurs

Question 11

What is sympatric speciation?

Answer 11

Subpopulations diverge despite no geographical separation.

Question 12

What is an example of speciation?

Answer 12

Two species of gull derived from common ancestry in Siberia, recognised as two distinct species in Northern Europe, cannot interbreed. However, linked along their range as freely interbreeding subspecies.

Question 13

Speciation on islands?

Answer 13

Islands offer a perfect setting for distinct species to evolve due to isolation. Adaptive radiation - rapid evolution of many species from a single ancestral species, often occurs on islands with many new ecological opportunities. E.g. Darwin’s finches on Galapagos. Phenotypes adapted to different diets, niches filled by other species elsewhere.

Question 14

How did speciation occur on Hawaiian islands?

Answer 14

As islands formed, drosophila populations became isolated and new species arose. Intersecting roles of geological forces, time, chance, evolutionary processes. Islands show us historical element in match between species and environment ; not just one perfect organism for each environment.

Question 15

Over what distances can isolation through geographical processes play out?

Answer 15

Larger scales, due to the movement of land masses through deep geological time.

Question 16

What needs to be considered to understand why species occur where they do?

Answer 16

Deep history (geological time). Origination of different groups of large flightless birds can be linked to movement of continents separating populations and allowing independent evolution.

Question 17

What role do historical factors have?

Answer 17

Species distribution adjust to past climate fluctuations. Distributions may not have reached equilibrium. Species now face much faster anthropogenic climate change beyond Pleistocene conditions.

Question 18

What is convergent evolution?

Answer 18

The match between the characters of organisms and their environment can be seen in different groups solving challenges in similar ways. E.g. various different plant families have modified organs to climb.

Question 19

What is parallel evolution?

Answer 19

When separate groups radiate in a similar way after they have become isolated, despite evolving independently, two groups can be faced with similar challenges and opportunities resulting in similar forms, lifestyles, ecological roles. This illustrates how given the same starting point and template of environmental opportunities the process of evolution can result in similar but not identical solutions.

Question 20

What are biomes? And what can they be?

Answer 20

Broad ecological zones characterised by communities of flora and fauna with characteristics broadly shaped by and matching their environments. Similar environments in different parts of the world leads to similar types of communities. Terrestrial, freshwater, marine.

Question 21

What are biomes characterised by?

Answer 21

Organisms, broad classification systems attempt to group species by their characteristics. E.g. Raunkiers classification of plant life forms based on position of bud during cold or dry seasons. The spectrum of raunkiers life forms varies across biomes, reflecting the match between life forms and environmental conditions. Biomes all consist of a variety of life forms, but the relative number of species of each varies with biome.

Question 22

How is their diversity in communities?

Answer 22

Species can coexist by filling diverse ecological roles. Coexistence of species constructed in a similar way can be explained by : environmental heterogeneity (variation) in space and time, niche partitioning similar species using resources and the environment in different ways.