A4.2 Conservation of biodiversity questions for IB Biology

Which is an example of genetic diversity?

Students investigated whether urbanization affects plant biodiversity. They chose five areas of unmown grassland, in parks and on road verges, at increasing distances from the centre of a large city. At each site they placed ten 1 m × 1 m quadrats at random and recorded the number of plant species in each quadrat.

Biodiversity can be considered at several levels.

Which statements about the number of species on Earth are supported by current evidence?

I. Most species alive today have not yet been named and described.
II. Fossil evidence suggests that more species are alive now than at any time in the past.
III. More than half of all the species that have ever existed are alive today.

Bird surveys are often carried out by citizen scientists. In a study of their reliability, twelve 1 km transects were surveyed on the same mornings by a trained ecologist, a novice volunteer (less than one year of experience) and an experienced volunteer (more than five years). They walked each transect separately, at the same pace, one after another, and the order in which they walked was changed each day. Each recorded every bird species seen or heard.

Photographs and sound recordings were used to check identifications. The percentage of records that were misidentifications was 1.2 % for the trained ecologists, 2.6 % for the experienced volunteers and 9.8 % for the novice volunteers.

Two captive breeding populations of an endangered antelope were each started from the same number of founders taken from the wild. In population M, animals were exchanged with other zoos every generation, following a breeding plan. Population N was kept isolated. Genetic diversity was measured in each generation as the mean heterozygosity: the proportion of gene loci at which an individual has two different alleles.