Twins and higher–order multiple pregnancies account for approximately 3% of all gestations in the United States (Ananth et al, 2004) and seem to be stabilized since 2006 after a dramatically increase since the beginning of the 1970s (Vayssière et al, 2011). There are two main causes for the change in the rate of multiple pregnancies: advanced maternal age and use of assisted reproductive techni...

The information and views set out in this publication are those of the author(s) and do not necessarily reflect the official opinion of the Commission. The Commission does not guarantee the accuracy of the data included in this study. Neither the Commission nor any person acting on the Commission's behalf may be held responsible for the use which may be made of the information contained therein.

Species are separated by reproductive isolation as well as by more 'ordinary' differences in morphology and behavior that play no necessary role in blocking gene flow. Although a great deal is now known about the genetics of reproductive isolation, we are only beginning to understand the genetic basis of ordinary phenotypic differences between species. I review what is known about the number of...

We investigate two methods of measuring fitness in evolutionary games played among members of a finite population. Classical notions of stability account for the action of selection only, and use immediate reproductive gains as a measure of fitness. This classical interpretation of fitness is what we call reproductive fitness (RF), and is found in the early studies of evolutionary stability in ...