IB Biology HL B4.2 Ecological niches Questions

Aedes japonicus and Aedes albopictus are invasive mosquito species that have recently become established in Western Europe. A. japonicus is more suited to the cooler regions in central Europe, while A. albopictus is adapted to warmer temperatures of the Mediterranean regions.

Outline two other ways, apart from preferred climate, in which the niches of these species may differ.

Marine sediments form at the bottom of oceans. These sediments contain organic material from the surface waters. Scientists analysed samples drilled from the floor of the north Pacific Ocean, representing 86 million years of sedimentation. Graph A shows the data for oxygen concentrations in 28 metres of sediment and graph B shows the oxygen consumption per cell in 22 metres of sediment measured in femtomoles ( $\mathrm{fmol}=10^{-15} \mathrm{~mol}$ ).

Suggest reasons for the differences in oxygen consumption between the cells at 2 metres and at 22 metres.

Which group(s) produce(s) oxygen as a by-product of photosynthesis?

I. Algae
II. Cyanobacteria
III. Fungi

The photograph shows Japanese knotweed, Reynoutria japonica, which is native to Japan, China and Korea. It has been introduced into other regions of the world and is now an invasive alien species in parts of Europe and North America. Dense groups of stems often develop with a height of up to 3 metres, which prevent other plants from growing.

Some insect species form interspecific relationships with Reynoutria japonica. Identify the relationship with these insect species:

Aphalara itadori, which feeds on the shoots and young leaves of Reynoutria japonica.

The diagram shows the flow of energy between some Arctic species.

Which organism is a mixotroph?

The statement is about the role of some bacteria in ecosystems.
> "Bacteria play an important role in recycling nutrients in ecosystems. They live on organic wastes and dead organisms and digest their molecules. They then absorb some of these molecules for their own metabolism, and the rest is used by other organisms."

What is the mode of nutrition of these bacteria?

The graph shows the effect of temperature on the growth rate of microorganisms in a biogas batch fermenter.

State the type of microorganism needed to form biogas.

Mutualisms are interactions between different species that provide benefits for both partners. A study was undertaken of the mutualism between four species of the host tree Acacia and six species of the ant Pseudomyrmex. Mutualistic ant species were compared to parasitic ant species of the same genus. Both groups of ants live inside the hollow thorns of the Acacia and eat the extrafloral nectar produced by the tree. Mutualistic ant species defend the Acacia from herbivores, while parasitic ant species do not.

The larval stage of the fly Eurosta solidaginis develops in the plant Solidago altissima.

The larva secretes a chemical which causes plant tissue to grow around it forming a swelling called a gall. The gall provides the developing insect with protection from predators.

The E. solidaginis fly is preyed upon by the parasitic wasp Eurytoma gigantea. The graph shows the relationship between gall diameter and the percentage of flies that avoid predation by E. gigantea.

Describe the relationship between gall diameter and percentage survival of E. solidaginis.

The Corsican nuthatch (Sitta whiteheadi) lives only on the island of Corsica in Corsican pine (Pinus nigra laricio) forests and groves of Maritime pine (Pinus pinaster).
Corsican nuthatch (S. whiteheadi)

A study looked at the relative importance of a range of factors affecting the distribution of the Corsican nuthatch. The relative importance of each factor was derived from how strongly the factor and the distribution of the nuthatch were correlated.

The Corsican pine (P. nigra laricio) has suffered large distribution losses due to human activity, intensively managed forests and wildfires. Thus, its realized niche is likely to be different from its fundamental niche. Distinguish between realized and fundamental niches.

In Wales, UK, the grey squirrel (Sciurus carolinensis) is an alien species and the red squirrel (Sciurus vulgaris) is endemic. The maps show the distribution of red and grey squirrels in 1945 and 2010.

The niches of the red and grey squirrels overlap. Explain the concept of competitive exclusion with respect to the changes in squirrel distribution shown in the maps.