Please explain how the following factors associate with life history: Natural selection, environment, population density, abundance and habitat.

It seems as if these concepts should be discussed in whatever textbook you are using. If not, you can look up each of the concepts and relate them to life history <http://en.wikipedia.org/wiki/Life_history>.

I searched Google under the key words "'life history' 'Natural selection'" to get these possible sources:

http://www.bioone.org/perlserv/?request=get-abstract&issn=0014-3820&volume=055&issue=02&page=0423
http://members.iinet.net.au/~sejones/histry04.html
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=14604592&dopt=Abstract
http://www.edge.org/3rd_culture/gould/gould_p2.html
http://www.senescence.info/evolution.html

You can do similar searches for life history combined with your other key words. If you do not have this capability, let us know and we will provide you with other sources.

I hope this helps. Thanks for asking.