Speciation questionsSpeciation questions

Easy one; NCEA 2008Easy one; NCEA 2008There 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.

NCEA 2008NCEA 2008 There are nine species of plants in the genus There are nine species of plants in the genus Pachycladon. Pachycladon. One of One of

these species is endemic to Tasmania, while the rest are endemic to these species is endemic to Tasmania, while the rest are endemic to the South Island of New Zealand. They have evolved within the last 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 3.5 million years, during the last Ice Age and when the Southern Alps were forming. The species have different physical features and Alps were forming. The species have different physical features and are found in different habitats. For example, they grow on different are found in different habitats. For example, they grow on different types of soil and rock.types of soil and rock.

(f) Discuss how this group of species could have (f) Discuss how this group of species could have evolved. In your answer consider: evolved. In your answer consider:

• • geological events geological events • • selection pressures.selection pressures.

Keywords to includeKeywords to include Gene flowGene flow Allele frequenciesAllele frequencies Geographic isolationGeographic isolation Selection pressuresSelection pressures Reproductive isolating Reproductive isolating

mechanismsmechanisms Adaptations Adaptations

How they are relatedHow they are related Geographical barriers stop gene flow (new Geographical barriers stop gene flow (new

individuals entering the population).individuals entering the population). Geographical barriers may lead to different selection Geographical barriers may lead to different selection

pressures between the populations (because of niche pressures between the populations (because of niche differentiation and the production of new habitats). differentiation and the production of new habitats).

Different selection pressures among populations lead Different selection pressures among populations lead to different adaptations becoming favoured in each to different adaptations becoming favoured in each population.population.

These selection pressures change the allele These selection pressures change the allele frequency within each population.frequency within each population.

Over time populations will always develop Over time populations will always develop reproductive isolating mechanisms making them reproductive isolating mechanisms making them individual species. individual species.

What to do to get to M What to do to get to M and Eand E You must include all keywords You must include all keywords

that we discussed before AND that we discussed before AND named examples of habitats and named examples of habitats and selection pressures the selection pressures the populations may face that may populations may face that may cause speciation. cause speciation.

A and MA and M AchievedAchieved Describes how this group Describes how this group

of species could have of species could have evolved considering a evolved considering a geological event OR a geological event OR a selection pressures, eg:selection pressures, eg:

The southern alps being The southern alps being formed created new habitats / formed created new habitats / niches.niches.

Isolated populations have Isolated populations have different selection pressures.different selection pressures.

During formation of the During formation of the southern alps groups of southern alps groups of PachycladonPachycladon may have been may have been geographically isolated.geographically isolated.

MeritMerit Explains how this group of Explains how this group of

species could have evolved species could have evolved considering geological considering geological events and a specific events and a specific selection pressure, eg:selection pressure, eg:

The southern alps being The southern alps being formed created new habitats / formed created new habitats / niches.niches.

These had their own selection These had their own selection pressures such as different soil pressures such as different soil types which acted on the types which acted on the populations causing them to populations causing them to adapt to their specific niches adapt to their specific niches causing genetic / phenotypic causing genetic / phenotypic differences sufficient that the differences sufficient that the two populations can no longer two populations can no longer interbreed. interbreed.

ExcellenceExcellence Discusses how this Discusses how this PachycladonPachycladon group of species group of species

could have evolved considering TWO geological could have evolved considering TWO geological events and specific selection pressures, eg:events and specific selection pressures, eg:

An ancestral An ancestral PachycladonPachycladon population originally in Australia population originally in Australia was able to disperse to NZ. The southern alps being formed was able to disperse to NZ. The southern alps being formed and lowered sea levels during an ice age created many new and lowered sea levels during an ice age created many new cooler / wetter habitats / niches. The new niches had cooler / wetter habitats / niches. The new niches had different selection pressures such as different rock substrate different selection pressures such as different rock substrate acting on the populations. Adaptation to these different acting on the populations. Adaptation to these different niches causedniches caused genetic / phenotypic differences sufficient genetic / phenotypic differences sufficient that the two populations can no longer interbreed. As there that the two populations can no longer interbreed. As there is is reproductive isolation between the populations speciation reproductive isolation between the populations speciation has occurred.has occurred.

Another easy one; Another easy one; NCEA 2008NCEA 2008

New Zealand has at least 37 species of geckos in two New Zealand has at least 37 species of geckos in two genera, genera, Hoplodactylus Hoplodactylus and and NaultinusNaultinus. . Hoplodactylus Hoplodactylus has the highest species diversity of has the highest species diversity of all New Zealand’s terrestrial vertebrates. Geckos all New Zealand’s terrestrial vertebrates. Geckos are ecologically diverse and found in almost all are ecologically diverse and found in almost all available terrestrial habitats.available terrestrial habitats.

DNA data suggest that adaptive radiation in geckos DNA data suggest that adaptive radiation in geckos began about 24 million years ago, a time when New began about 24 million years ago, a time when New Zealand consisted of a series of low-lying islands. Zealand consisted of a series of low-lying islands. Since then New Zealand has experienced: Since then New Zealand has experienced: substantial rises and falls in sea level; a period of substantial rises and falls in sea level; a period of mountain-building and volcanic activitymountain-building and volcanic activity

(c) Identify the form of speciation that has given rise to New Zealand’s geckos

New Zealand has at least 37 species of geckos in two New Zealand has at least 37 species of geckos in two genera, genera, Hoplodactylus Hoplodactylus and and NaultinusNaultinus. . Hoplodactylus Hoplodactylus has has the highest species diversity of all New Zealand’s the highest species diversity of all New Zealand’s terrestrial vertebrates. Geckos are ecologically diverse terrestrial vertebrates. Geckos are ecologically diverse and found in almost all available terrestrial habitats.and found in almost all available terrestrial habitats.

DNA data suggest that adaptive radiation in geckos began DNA data suggest that adaptive radiation in geckos began about 24 million years ago, a time when New Zealand about 24 million years ago, a time when New Zealand consisted of a series of low-lying islands. Since then New consisted of a series of low-lying islands. Since then New Zealand has experienced: substantial rises and falls in sea Zealand has experienced: substantial rises and falls in sea level; a period of mountain-building and volcanic activitylevel; a period of mountain-building and volcanic activity

(d) Discuss the evolution of (d) Discuss the evolution of Hoplodactylus Hoplodactylus geckos in geckos in New Zealand. You should consider the impact of New Zealand. You should consider the impact of the geographical isolating mechanisms listed the geographical isolating mechanisms listed above, and the evolution of reproductive isolating above, and the evolution of reproductive isolating mechanisms between the species.mechanisms between the species.

A and MA and M AchievedAchieved Describes the evolution of the Describes the evolution of the

HoplodactylusHoplodactylus geckos in NZ (in geckos in NZ (in relation to the impact of the relation to the impact of the geographical isolating geographical isolating mechanisms OR the evolution mechanisms OR the evolution of reproductive isolating of reproductive isolating mechanisms) , eg:mechanisms) , eg:

Populations were isolated on low-Populations were isolated on low-lying islands which caused allele lying islands which caused allele frequencies to change.frequencies to change.

Mountain building formed new Mountain building formed new habitats with new selection habitats with new selection pressures.pressures.

NZ populations were separated for NZ populations were separated for long periods of time enabling long periods of time enabling reproductive / behavioural reproductive / behavioural isolation.isolation.

MeritMeritExplains the evolution of Explains the evolution of the the HoplodactylusHoplodactylus geckos in geckos in NZ (in relation to the impact of NZ (in relation to the impact of the geographical isolating the geographical isolating mechanisms AND the evolution mechanisms AND the evolution of reproductive isolating of reproductive isolating mechanisms) , eg:mechanisms) , eg:

Populations were isolated on low-Populations were isolated on low-lying islands during interglacial lying islands during interglacial periods which caused allele periods which caused allele frequencies to change leading to frequencies to change leading to gecko speciation.gecko speciation.

NZ gecko populations separated NZ gecko populations separated for long periods of time when NZ for long periods of time when NZ was a series of low-lying islands was a series of low-lying islands subject to different selection subject to different selection pressures. Due to the populations pressures. Due to the populations adapting to the different adapting to the different environments reproductive environments reproductive isolation mechanisms have isolation mechanisms have developed. developed.

ExcellenceExcellence Discusses the evolution of the Discusses the evolution of the HoplodactylusHoplodactylus geckos geckos

in NZ by considering how at least TWO geographical in NZ by considering how at least TWO geographical isolating mechanisms led to the evolution of isolating mechanisms led to the evolution of reproductive isolating mechanisms, eg:reproductive isolating mechanisms, eg:

When NZ was a series of low-lying islands the gecko When NZ was a series of low-lying islands the gecko population was isolated and subjected to different selection population was isolated and subjected to different selection pressures. These populations accumulated genetic pressures. These populations accumulated genetic differences and developed reproductive isolating differences and developed reproductive isolating mechanisms (such as post/pre-zygotic). Sea levels dropped mechanisms (such as post/pre-zygotic). Sea levels dropped / mountain building / volcanic activity created new habitats / / mountain building / volcanic activity created new habitats / into which gecko populations could disperse. Different into which gecko populations could disperse. Different selection pressures in each would have caused further selection pressures in each would have caused further reproductive isolation between populations. reproductive isolation between populations.

NCEA 2007NCEA 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.

BrainstromBrainstrom What geographical barriers have What geographical barriers have

occurred?occurred? What has happened to the What has happened to the

habitats and environment over habitats and environment over this time throughout the south this time throughout the south island?island?

How to answer this How to answer this questionquestion Define adaptive radiation Define adaptive radiation

and how/why it occursand how/why it occurs What glaciers and What glaciers and

mountain building would mountain building would do to one large original do to one large original population.population.

Describe the different Describe the different selection pressures on east selection pressures on east and west coastand west coast

Discuss with examples the Discuss with examples the role isolating mechanisms role isolating mechanisms would play in speciation would play in speciation occurring.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.

AchievedAchieved Defines adaptive radiation as a Defines adaptive radiation as a

new species evolving from a new species evolving from a common ancestor to exploit common ancestor to exploit newly available niches with new newly available niches with new adaptations adaptations

MeritMerit Explains the impact of specific Explains the impact of specific

geological history. geological history. Glaciers or mountain building splitting Glaciers or mountain building splitting

populations into smaller groups. populations into smaller groups. OR OR The exposure to different selection The exposure to different selection

pressures e.g. as East and West pressures e.g. as East and West differentiate due to mountain differentiate due to mountain building. building.

ExcellenceExcellence Evaluation of reproductive Evaluation of reproductive

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

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

AchievedAchieved 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.

MeritMerit 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.

ExcellenceExcellence 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.

Patterns of evolutionPatterns of evolution Co-evolutionCo-evolution Divergent evolution (& adaptive Divergent evolution (& adaptive

radiation)radiation) Convergent evolutionConvergent evolution

NCEA questionsNCEA questions What to doWhat to do Name the pattern of evolution Name the pattern of evolution

and define itand define it Explain why this is an example Explain why this is an example

referring specifically to the referring specifically to the organisms you have been given. organisms you have been given.