Inspire Biology

(l) NSP-RF/Alamy Stock Photo; (r) Carl & Ann Purcell/Corbis Documentary/Getty Images

COMMUNICATE SCIENTIFIC IDEAS

Create a poster that shows why

conservationists are concerned about the

population numbers of northern and reticulated

giraffes. How would losing one of these types

of giraffes affect biodiversity in Africa?

More Species—

Fewer Individuals

Reclassification

Scientists have long thought all giraffes

belonged to one species that could be

divided into nine subspecies. However, new

evidence has led scientists to reconsider this

classification. Analysis of DNA from 190 wild

giraffes indicates that there are four genetically

distinct giraffe groups.

With the discovery of these genetically

isolated groups, some scientists think giraffes

should be categorized into four species: the

northern giraffe, the southern giraffe, the

reticulated giraffe, and the Masai giraffe.

However, because these four groups are

not reproductively isolated—interbreeding

between these groups is considered rare but

possible—some scientists still think all giraffes

belong to only one species.

The genetic findings have brought new

attention to conservation efforts. The total

number of wild giraffes has dropped from

about 150,000 to less than 90,000 in the

past 30 years, but giraffes have not been

considered a species of great concern

because their numbers are still large

compared to other species. With the discovery

of four genetically distinct groups, concern

has increased because the population

numbers of some of the groups are low.

For example, there are less than 5,000 northern

giraffes left in Africa, making them one of the

most endangered large mammals in the world.

Giraffe populations are dropping due to loss

of habitat, civil unrest, livestock overgrazing,

and hunting. Conservationists are working to

protect remaining populations. For example,

conservationists are working with the San

Diego Zoo Institute for Conservation Research

to sequence the giraffe genome.

Giraffes are found in grasslands throughout

Africa. These animals—the tallest in the

world—eat leaves, seeds, and fruits. They

need to consume hundreds of pounds of

food per week to survive.

SCIENTIFIC BREAKTHROUGHS

Scientists have determined that there are four genetically

distinct giraffe groups, including the Masai giraffe (left) and

the reticulated giraffe (right).

Module 5 • Scientific Breakthroughs

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