Africa – over time

Please consider images to be copyrighted and ask permission to use or reproduce. I wish I could remember the source for the Africa habitat maps – they are valuable teaching tools. Thank you whoever you are. DEClapp

This is important – you can’t understand Africa without this!! It probably applies everywhere throughout the world but it is easy to see in Africa and I am doing a series of African posts right now … so here it is. Keep it in mind with all wildlife populations, distribution, migrations, extra-range sightings and more.

The climate changes.

It is the determining factor for vegetation types and thus feeding the animals that can live in specific places and eliminating those who can’t. Climate is long term. Dry periods and wet periods can last hundreds, even thousands of years. Modern African wildlife has been divided into sub-species and scattered populations by changes wrought over the past several thousand years. There have been dry periods and wet periods; long periods of dryness and long periods of wetness. What we see today is not permanent or static – it is merely what we see today. It will change and when it changes the animals and the plants will change as well. Populations will be divided as habitat grows or lessens. Divided populations will breed and evolve along their own track, depending on the local climate and its effects.

Look at these maps and note the changes in woodland habitat; in savanna habitat, and in tropical forest habitat. During dry periods (and today) the Sahara desert is significant. During a wetter period the desert is turned into a grassy savanna and associated woodlands. This was a time when lions and antelope lived in the northern part of Africa.

The wetter epochs saw tremendous increases in the size of the woodland and tropical forest habitats. The savanna land was pinched and the desert was squeezed northward. This situation allowed for an increase in woodland vegetation and animal species and divided the savannah animals into a southern group and an east-west group well to the north. When this sort of division lasts for tens of thousands of years the animals adapt as needed to their locations and often become something different from what they were originally. Thus we have different forms of Wildebeest, Hartebeest, Zebra, Impala, and Giraffes along a north-south line. This is the result of population isolation as the habitat constricted and was fragmented. When climate changes and a habitat grows these populations may spread and overlap. It will depend on the evolutionary circumstance as to whether the two new groups will recognize their shared heritage and interbreed. (These would be experiments that need hundreds of years of data collection.)

Today the African continent is somewhere in the middle; between humid and dry. Savannas are still divided by woodlands and thus there are two great savanna lands. The safari destinations in Kenya and Tanzania are in (central) East Africa and there is a lot of savanna there; the Maasai Mara and the Serengeti are iconic grasslands in East Africa. There is also a patch of savanna across the southern part of the continent. This is where the great game parks of Botswana, Zimbabwe, and Zambia are located. The country of South Africa has a nice variety of habitat types including mountains along the eastern edge and the Cape habitat in the very southern bit of the continent.

Each of the habitats provides specific circumstances that determine the metabolic and genetic requirements needed to survive.

The point is that these habitats change with climate change and then everything else changes as well. Deserts grow or contract. Woodlands grow or contract. Grasslands; the same. Each hiccup causes a great ripple through all the life forms associated with these landforms and ecological communities.