Body size is often constrained from evolving. Although artificial selection on body size in insects frequently results in a sizable response, these responses usually bear fitness costs. Further, these experiments tend to select only on size at one landmark age, rather than selecting for patterns of growth over the whole larval life stage. To address whether constraints may be caused by larval growth patterns rather than final size, we implemented a function-valued (FV) trait method of selection, in which entire larval growth curves from Tribolium were artificially selected. The selection gradient function used was previously predicted to give the maximal response and was implemented using a novel selection index in the FV framework. Results indicated a significant response after one generation of selection, but no response in subsequent generations. Correlated responses included increased mortality, increased critical weight, and decreased development time (DT). The lack of response in size and development time after the first generation was likely caused by increased mortality suffered in selected lines; we demonstrated that the selection criterion caused both increased body size and increased mortality. We conclude that artificial selection on continuous traits using FV methods is very efficient and that the constraint of body size evolution is likely caused by a suite of trade-offs with other traits.
Generation 0
Body mass measurements for tribolium larvae. In generation 0, these beetles have not yet undergone selection, but rather set a standard on which selection can be enacted to produce generation 1. Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen0Data_dryad.xls
Generation 1
Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen1Data_dryad.xlsx
Generation 2
Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen2Data_dryad.xlsx
Generation 3
Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen3Data_dryad.xlsx
Geneartion 4
Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen4Data_dryad.xlsx
Generation 4.2 (Gen 4 repeated)
Each row represents sequential mass measurements for a given individual. The column headings, in order, represent the beetled identification number (ID), its sex (Sex), the sire that produced it (Sire), the dam that produced it (DAM), the date of its egg hatch (HatchDate), the date of the first measurement (Date1), the age at first measurement (DSH1), the mass at first measurement (Mass1), the date of second measurement (Date2), etc. After larval measurements, information about the pupal and adult stages is listed in columns to the right: date of pupation (PubDate), age at pupation (DTP), pupal mass (PupMass), date of eclosion to the adult stage (EcDate), and age at eclosion to the adult stage (DTE). Any individuals who do not have a pupal mass measurement did not survive to pupation, and individuals without an eclosion date (but with a pupal mass measure) survived to pupation but not to eclosion.
Gen4.2Data_dryad.xlsx
