Group+2a

 Group 2: Siân Peck (Secretary), Katie Daughters, Sally Faulkner, Jane Hardwick and Chris Hughes.

__The Evolutionary Processes that Cause Polymorphism of Gastropod Shells in Natural Populations of__ __//Cepaea nemoralis//__ __in the Chiltern Hills.__

The obvious variability in colouration and markings on the shells of the same species of gastropod //Cepaea nemoralis//  has in the years been extremely useful in research in the field of population genetics (e.g. Cain & Sheppard, 1954 and Harvey, 1976). In addition to the clear polymorphism, the lack of the need for expensive genome processing, the limited movement capabilities of the gastropods and therefore ease of localised samplings, studies of //Cepaea//  have proved to be popular as a genetic model for other organisms, including humans. Studies on //Cepaea//  being theoretically idealistic and applicable to other areas of ecology also minimise impact and inevitable ethical problems on studying human populations. //Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> express a number of differing phenotypes, most noticeably on their shells (Lamotte, 1959). This categorises the species as polymorphic; variable phenotypes of <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">individuals exist <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> within a population. The evolutionary processes that brought about the origin of polymorphism in <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> remain to be the crux of research in this field unclear what you mean <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, the main argument dividing those favouring the solution of natural selection this is a bit vague... most scientists would accept that both processes operate, so what is the real issue? <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> and those supporting random processes (Jones, Leith & Rawlings, 1977). Here, the argument for selection acting on <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> and bringing about variability in shell colouring and banding in different habitats is further investigated. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Natural selection acts on populations, favouring genes which will be beneficial to survival of the individual (Darwin, 1859). In this study, several populations within two types of habitats will be analysed. In prediction, if natural selection is acting upon <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, individuals from the same habitat will be phenotypically similar, even if they are from different populations. Extending upon the same prediction, if the habitats are significantly what does that word mean in this context? different, the phenotype between the habitats will differ. If observations deviate from the anticipated situations be more precise, other random evolutionary processes will have to be brought into question poor phrasing , namely genetic drift and gene flow. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">To test the hypothesis, the area of experimentation held at least two types of habitats where <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> are adapted to survive is that not tautology? <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> and are numerous enough to obtain applicable samples (e.g. dense shrub and grassland). These differed enough to suggest that selection, for example visual or climatic, could occur given the differences in parameters of the two environments and hence provided at least two phenotypes due to niche adaptation vague, be more precise <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">. In addition to the two niche environments <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**,** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> the area presented at least two similar regions of each habitat type for comparison of populations from similar habitats in different areas be clearer. This distinguished further poor construction whether selection is acting on populations between grassland and shrub land. Variation between for example the shrub land populations, could be explained by selection for a parameter not tested, gene flow or genetic drift. Multiple samples were also be taken within each habitat and by trying to keep the habitat of populations sampled consistent it kept controllable variation between samples to a minimum. It is not possible to measure, soil pH or nutrient levels, however, where possible, it was important to try and sample at sites of similar altitude and ecology. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">In this paper, the origin of polymorphism of <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> is put under scrutiny in an aim to draw a conclusion for this example of population genetics how, using what logic. Three main contenders (selection, flow and drift) will be kept at the forefront but how will you tell whether the geographic patterns are the consenquence of a particular combination of processes, what is the underlying logic of the argument although it may become clear that other processes are at work which leads to further experimentation and discussion for the future. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Cain, A. J. & Sheppard, P. M. 1954. Natural Selection in <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Genetics Society of America// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**39** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 89-116. Darwin, C. 1859, On the origin of species by means of natural selection, or The preservation of favoured races in the struggle for life, D. Appleton & Co., New York. Harvey, P.H. 1976. Factors influencing the shell pattern polymorphism of the <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea nemoralis// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(L.) in East Yorkshire: A Test Case. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Heredity.// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**36** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 1-10 Jones, J.S. Leith, B. H. Rawlings, P. 1977. Polymorphism in <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//CEPAEA// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">: A problem with too many solutions. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Annual Review Ecology System.// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**8** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 109-148 Lamotte, M. 1959 ‘Polymorphism of Natural Populations of <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea nemoralis’// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cold Spring Harbour Symposia on Quantitative Biology// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**24** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 65-86 Revised Introduction: <span style="background-color: transparent; display: block; font-size: medium; margin-bottom: 0px; margin-left: 0px; margin-right: 0px; margin-top: 0px; white-space: normal;"><span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">The obvious variability in colouration and markings on the shells of the same species of gastropod <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea nemoralis// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> has in the years been extremely useful in research in the field of population genetics (e.g. Cain & Sheppard, 1954 and Harvey, 1976). In addition to the clear polymorphism (which removes the requirement for expensive genome processing) and the limited movement capabilities of the gastropods which therefore make localised sampling possible, studies of <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> have proved to be popular as a genetic model for other organisms, including humans. Studies on <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> being theoretically idealistic and applicable to other areas of ecology also take away inevitable ethical problems that occur when studying human populations. <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> express a number of differing phenotypes, most noticeably on their shells (Lamotte, 1959). This categorises the species as polymorphic; variable phenotypes of individuals that exist within a population. The evolutionary processes that maintain polymorphism in <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> are the main focal point of most research being carried out in the field.

There are three main processes that can lead to polymorphism: natural selection, genetic drift and gene flow. Here, the argument for selection acting on <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> is further investigated. Natural selection acts on populations, favouring genes which will be beneficial to survival of the individual (Darwin, 1859). In this study, several populations within two types of habitats will be analysed. In prediction, if natural selection is acting upon <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, individuals from the same habitat will be phenotypically similar, even if they are from different populations. Extending upon the same prediction, if the habitats are different, the phenotype between the habitats will differ. If the phenotype frequency from similar habitats are significantly different and the frequency from samples or not significantly different then this could imply that selection is acting. However, if there is no significant correlation between phenotype frequency and habitat type, it is possible that genetic drift and/or gene flow are the cause. Our hypothesis states that selection is causing a significant difference within <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> between two habitats.

To test the hypothesis, various samples from two distinctly different habitats have been analysed. If these display significantly different phenotypes, after statistical analysis, it would suggest that selection, for example visual or climatic, has been occurring hence the presence of two distinct phenotypes that are highly adapted to their niche environments. Multiple samples have also been taken within each habitat as well as trying to keep the habitat of each population sampled consistent, to keep extraneous variables as constant as possible: similar altitude and ecology.

In this paper, the mechanism of polymorphism is put under scrutiny in an aim to draw a conclusion as to which of the three main processes is acting on <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: Calibri; font-size: 12pt; font-style: normal; font-weight: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;"> : selection, flow or drift. This would be shown if chi squared analysis of the data shows a significant level of difference between habitats at a probability rate that exceeds 5% chance. Should the experiment not produce conclusive results, the investigation will need to be further explored in later research. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">Cain, A. J. & Sheppard, P. M. 1954. Natural Selection in <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Genetics Society of America// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**39** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 89-116. Darwin, C. 1859, On the origin of species by means of natural selection, or The preservation of favoured races in the struggle for life, D. Appleton & Co., New York. Harvey, P.H. 1976. Factors influencing the shell pattern polymorphism of the <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea nemoralis// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">(L.) in East Yorkshire: A Test Case. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Heredity.// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**36** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 1-10 Jones, J.S. Leith, B. H. Rawlings, P. 1977. Polymorphism in <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//CEPAEA// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">: A problem with too many solutions. <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Annual Review Ecology System.// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**8** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 109-148 Lamotte, M. 1959 ‘Polymorphism of Natural Populations of <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cepaea nemoralis’// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">//Cold Spring Harbour Symposia on Quantitative Biology// <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">**24** <span style="background-color: transparent; color: #000000; font-family: 'Times New Roman'; font-size: 10pt; font-style: normal; font-weight: normal; line-height: normal; text-decoration: none; vertical-align: baseline; white-space: pre-wrap;">, pp. 65-86