Speciation questions

1. Speciation questions

2. Easy one; NCEA 2008 There are two species of Howea palm on Lord Howe Island. They evolved there from a common ancestor between one and two million years ago. Scientists have found that the two Howea species are found in the same area. • (c) Identify the type of speciation that is most likely to have occurred in Howea palms.

3. NCEA 2008 • There are nine species of plants in the genus Pachycladon. One of these species is endemic to Tasmania, while the rest are endemic to the South Island of New Zealand. They have evolved within the last 3.5 million years, during the last Ice Age and when the Southern Alps were forming. The species have different physical features and are found in different habitats. For example, they grow on different types of soil and rock. • (f) Discuss how this group of species could have evolved. In your answer consider: • • geological events • • selection pressures.

4. Keywords to include • Gene flow • Allele frequencies • Geographic isolation • Selection pressures • Reproductive isolating mechanisms • Adaptations

5. How they are related • Geographical barriers stop gene flow (new individuals entering the population). • Geographical barriers may lead to different selection pressures between the populations (because of niche differentiation and the production of new habitats). • Different selection pressures among populations lead to different adaptations becoming favoured in each population. • These selection pressures change the allele frequency within each population. • Over time populations will always develop reproductive isolating mechanisms making them individual species.

6. What to do to get to M and E • You must include all keywords that we discussed before AND named examples of habitats and selection pressures the populations may face that may cause speciation.

7. Achieved Describes how this group of species could have evolved considering a geological event OR a selection pressures, eg: The southern alps being formed created new habitats / niches. Isolated populations have different selection pressures. During formation of the southern alps groups of Pachycladon may have been geographically isolated. Merit Explains how this group of species could have evolved considering geological events and a specific selection pressure, eg: The southern alps being formed created new habitats / niches. These had their own selection pressures such as different soil types which acted on the populations causing them to adapt to their specific niches causing genetic / phenotypic differences sufficient that the two populations can no longer interbreed. A and M

8. Excellence • Discusses how this Pachycladon group of species could have evolved considering TWO geological events and specific selection pressures, eg: • An ancestral Pachycladon population originally in Australia was able to disperse to NZ. The southern alps being formed and lowered sea levels during an ice age created many new cooler / wetter habitats / niches. The new niches had different selection pressures such as different rock substrate acting on the populations. Adaptation to these different niches caused genetic / phenotypic differences sufficient that the two populations can no longer interbreed. As there is reproductive isolation between the populations speciation has occurred.

9. Another easy one; NCEA 2008 New Zealand has at least 37 species of geckos in two genera, Hoplodactylus and Naultinus. Hoplodactylus has the highest species diversity of all New Zealand’s terrestrial vertebrates. Geckos are ecologically diverse and found in almost all available terrestrial habitats. DNA data suggest that adaptive radiation in geckos began about 24 million years ago, a time when New Zealand consisted of a series of low-lying islands. Since then New Zealand has experienced: substantial rises and falls in sea level; a period of mountain-building and volcanic activity (c) Identify the form of speciation that has given rise to New Zealand’s geckos

10. New Zealand has at least 37 species of geckos in two genera, Hoplodactylus and Naultinus. Hoplodactylus has the highest species diversity of all New Zealand’s terrestrial vertebrates. Geckos are ecologically diverse and found in almost all available terrestrial habitats. DNA data suggest that adaptive radiation in geckos began about 24 million years ago, a time when New Zealand consisted of a series of low-lying islands. Since then New Zealand has experienced: substantial rises and falls in sea level; a period of mountain-building and volcanic activity (d) Discuss the evolution of Hoplodactylus geckos in New Zealand. You should consider the impact of the geographical isolating mechanisms listed above, and the evolution of reproductive isolating mechanisms between the species.

11. Achieved Describes the evolution of the Hoplodactylus geckos in NZ (in relation to the impact of the geographical isolating mechanisms OR the evolution of reproductive isolating mechanisms) , eg: Populations were isolated on low-lying islands which caused allele frequencies to change. Mountain building formed new habitats with new selection pressures. NZ populations were separated for long periods of time enabling reproductive / behavioural isolation. MeritExplains the evolution of the Hoplodactylus geckos in NZ (in relation to the impact of the geographical isolating mechanisms AND the evolution of reproductive isolating mechanisms) , eg: Populations were isolated on low-lying islands during interglacial periods which caused allele frequencies to change leading to gecko speciation. NZ gecko populations separated for long periods of time when NZ was a series of low-lying islands subject to different selection pressures. Due to the populations adapting to the different environments reproductive isolation mechanisms have developed. A and M

12. Excellence • Discusses the evolution of the Hoplodactylus geckos in NZ by considering how at least TWO geographical isolating mechanisms led to the evolution of reproductive isolating mechanisms, eg: • When NZ was a series of low-lying islands the gecko population was isolated and subjected to different selection pressures. These populations accumulated genetic differences and developed reproductive isolating mechanisms (such as post/pre-zygotic). Sea levels dropped / mountain building / volcanic activity created new habitats / into which gecko populations could disperse. Different selection pressures in each would have caused further reproductive isolation between populations.

13. NCEA 2007 • There are many endemic species of cockroach (genus Celatoblatta) in the South Island (below), which have undergone adaptive radiation over the last 6 million years. During this time, the region was first warm and wet, and then heavily glaciated during the last ice age • (c) Discuss how geological history has affected the adaptive radiation and distribution of Celatoblatta species in the South Island.

14. Brainstrom • What geographical barriers have occurred? • What has happened to the habitats and environment over this time throughout the south island?

15. Define adaptive radiation and how/why it occurs What glaciers and mountain building would do to one large original population. Describe the different selection pressures on east and west coast Discuss with examples the role isolating mechanisms would play in speciation occurring. There are many endemic species of cockroach (genus Celatoblatta) in the South Island (below), which have undergone adaptive radiation over the last 6 million years. During this time, the region was first warm and wet, and then heavily glaciated during the last ice age (c) Discuss how geological history has affected the adaptive radiation and distribution of Celatoblatta species in the South Island. How to answer this question

16. Achieved • Defines adaptive radiation as a new species evolving from a common ancestor to exploit newly available niches with new adaptations

17. Merit • Explains the impact of specific geological history. • Glaciers or mountain building splitting populations into smaller groups. • OR • The exposure to different selection pressures e.g. as East and West differentiate due to mountain building.

18. Excellence • Evaluation of reproductive isolation is discussed with reference to the way that species reproductive isolation or genetic differences are maintained for those species using pre or post-zygotic mechanisms to justify the outcome.

19. QUESTION ONE 2010 Four species of crested penguin are found on various New Zealand islands, which range in climate from temperate to sub-Antarctic and have differing environmental conditions. Some information on crested penguins is included below. • Using examples from the table above, discuss the different reproductive isolating mechanisms that may operate among the New Zealand penguin species. Include in your answer: • • how speciation may have occurred • • the role of reproductive isolating mechanisms • • how pre and post zygotic isolating mechanisms can work together.

20. Achieved • ONE of: • Describes types of speciation (a) • Eg penguins could undergo speciation in different places (allopatric speciation) or in the same place by occupying different niches/habitats (sympatric speciation). BOTH types needed • Describes isolating mechanisms for each type (a) • Eg, geographical boundaries could keep birds from interbreeding. • AND • ONE of: • Temporal differences may result in breeding at different times. • Different mating rituals may isolate groups of birds. • Physical differences may make mating impossible. • Hybrid sterility may inhibit breeding. • Hybrid inviability may stop interbreeding. • Hybrid breakdown may prevent interbreeding. • Polyploidy.

21. Merit • Description of types or isolating mechanisms AND explanation of how this leads to speciation for both. (m) • Any 2 RIMs from (a) can be used for M but must have gained A by including both allopatric and sympatric example. • Eg penguins based on different islands are unlikely to mate. Penguins that live in the same place but have different niches will become adapted for their niche. In both situations gene flow is limited, and over time different selection pressures / accumulation of genetic differences result in enough change, so that they cannot interbreed.

22. Excellence • Discussion links sympatric and allopatric speciation to isolating mechanisms and gives examples of species for at least one and how post-zygotic and pre-zygotic mechanisms work together. (e) • Eg sympatric speciation is where species don’t interbreed due to niche differences. For instance, they may breed at different times, which means that there is limited gene flow. Eventually, genetic changes will mean they cannot interbreed. Snares and Rockhopper is an example of allopatric speciation, as they live on different islands. Because they now have different crests, the Rockhopper and Snares penguins don’t recognise each other as a mate, which is good, as if they did, the offspring may be infertile, so they have wasted time and energy.

23. Patterns of evolution • Co-evolution • Divergent evolution (& adaptive radiation) • Convergent evolution

24. NCEA questions • What to do • Name the pattern of evolution and define it • Explain why this is an example referring specifically to the organisms you have been given.