Biological Oceanography

%Set    matrices    of  individual  vectors for males   and females,

%If males(x,1)=1,   that    male    is  alive;  =0  means   dead.

    males=zeros(m,3);   males(:,1)=1;   fems=zeros(f,3);    fems(:,1)=1;    

%Zero   some    summing registers

    em1=0;  em2=0;  ef1=0;  ef2=0;

    for i=1:45  %Loop   over    45  number  days    of  mating  

%To apply   differential    mortality   to  males   &   females,    loop    over    both:

%   remove  all %   (comment    signs)  down    to  storage process part.

%   PdeathM =   0.15;   PdeathF=0.015   (try    changing    these)

%for    j=1:m

%g=rand;    g   is  compared    to  probability of  death,  for males   15%

%   if  males(j,1)==1   &&  g<=PdeathM; males(j,1)=0;   end

%end

%for    k=1:f;

%   g=rand; for females

%   if  fems(k,1)==1    &&  g<=PdeathF; fems(k,1)=0;    end

            for j=1:m   %loop   over    all males

%if males(j,1)==1   %this   skips   dead    males

            for k=1:f   ;   %loop   over    all females

                %if fems(k,1)==1    %skip   dead    females

                    Ctest=rand; %ctest

                    if  Ctest<C

                            if  fems(k,2)==0    

fems(k,2)=1;    males(j,2)=males(j,2)+1;

elseif  fems(k,2)==1    ;   

fems(k,3)=1;    fems(k,1)=0;    males(j,3)=males(j,3)+1;    

                                end

                            end

%end

                    end

%end

            end

        end %Storage    processes:

for j=1:m   %Get    frequency   distribution    of  first   femle   matings per male

        for n=0:6

                if  males(j,2)==n;  MpM(h,n+1)=MpM(h,n+1)+1;    end

        end

        if  males   (j,1)>=8;   MpM(h,8)=MpM(h,8)+1;    end

    end 

    for k=1:f   %Total  up  matings per female:

                ef1=ef1+fems(k,2);  ef2=ef2+fems(k,3);

    end

Storem1(h)=em1; Storem2(h)=em2; Storef1(h)=ef1; Storef2(h)=ef2;

h   %To show    program progress    in  the Command Window

MpM(h,1:8)  %List   matings per male    for current proportion  of  males,  h

end

MpM 

figure

plot(Propmales(:),Storef1(:),′r′);

xlabel(′Proportion  of  Males′)

ylabel(′Number  of  Females Mated,  1x=red, 2x=blue′)

hold    on

plot(Propmales(:),Storef2(:),′b′);

(^)
For the value of C = 4.5 × 10−6 per day for every possible male–female pair and no
mortality, running the model showed that the sex ratio producing the most females
fertilized once (probably enough to maximize egg output) is about 33% males (Fig.
4.13), but about 18% of females went unfertilized. It took relatively more males to
maximize the number of females mated twice (filling both sperm receptacles, a
feature of copepod reproduction, possibly the limit allowed by females). Thus, a more
demanding requirement for successful mating requires a greater proportion of males.