DOI: 10.5061/dryad.sn02v6xd5
title: Data from: Parental investment and body temperature explain encephalization in vertebrates

description: The massive increase in relative brain size during vertebrate evolution
 remains poorly understood. Given the high energetic costs of brain
 development, we predicted that encephalization (major evolutionary brain
 size expansion) is only possible in species capable of greater parental
 investment per offspring. Comparative analyses across all major vertebrate
 classes (N=2600 species) revealed that protecting or provisioning eggs or
 embryos is associated with larger newborns. Subsequent analyses confirmed
 that newborn size and adult brain size underwent correlated evolution in
 birds, mammals, and cartilaginous fishes, but not in other fishes,
 amphibians, and reptiles, even if the latter had large offspring. Thus,
 greater pre-hatching investment is necessary but not sufficient for
 encephalization in vertebrates. A second prediction from the high costs of
 brain tissue is that encephalization is impeded in species with low or
 fluctuating body temperatures. We found a positive relationship (albeit
 sometimes insignificant) between mean body temperature and brain size
 within all classes. A combined analysis across all vertebrates revealed
 significant and synergistic effects of body temperature and newborn size
 on brain size. In conclusion, encephalization became most pronounced in
 vertebrate lineages that can both produce large offspring, mostly
 reflecting internal fertilization, and sustain high body temperature,
 partly linked to endothermy.
description: # Data from: Parental provisioning is a precondition for major
 encephalization in vertebrates
 [https://doi.org/10.5061/dryad.sn02v6xd5](https://doi.org/10.5061/dryad.sn02v6xd5) This study presents comparative analyses across all major vertebrate classes, examining the impact of relative offspring size and egg/parental care behavior on the evolution of brain size. ## Description of the data and file structure **ParProv_Song_etal2025_Data_submit.xlsx** The dataset includes brain mass (**BrainMass.BrM..g.**) and body mass (**Bodymass.BdM..g.**) combined with offspring mass (**Offspring**). * **Offspring_note**: Indicates whether the offspring mass was calculated from hatchling/neonate mass or converted from egg volume. * For some species, adult brain specimens were unavailable. In such cases, the provided body mass (BodyMass.BdM.g) was often too small compared to common adult sizes, leading to an overestimation of relative offspring size. To address this, the common adult body mass (**AdultMass**) was used instead for evaluating relative offspring mass. * **AdultMass_note**: Specifies whether the adult mass was derived from 'Bodymass.BdM..g.' or common adult mass. * **Parental care behavior**: Categorized into five types in **EggCare5Cat**, with more detailed descriptions in **EggCare**. * **Fertilization model**: Classified as internal or external. * **Tb**: Refers to the preferred ambient temperature for fish and body temperature for amphibians, reptiles, birds, and mammals. * **BMR:** Represents the basal metabolic rate, measured in watts.\ **BEQ_scale** is the BMR value scaled to a standard body size and ambient temperature, following the equation provided by Yegian et al. (2024, *PNAS*). * **Temp** refers to the ambient temperature in degree C **Vertebrate_Phylogenetic_Trees.zip** Phylogenetic trees for each vertebrate class are included. **Code** * **ParProv_Song_etal2025_Code_submit.R**: Contains all analyses from Tables 1-2 and Tables S3-S16. * **ParProv_Song_etal2025_Plot_Code_submit.R**: Contains the code for generating all the figures. **Related links and data references** The following external sources are referenced in the dataset and correspond to information used for offspring size, adult mass conversion, egg care behavior, and fertilization type. These links were included in the data file and are listed here for accessibility and interpretation. **Offspring size references (Offspring.REF)** * *Heterodontus portusjacksoni*: Florida Museum\ [https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/heterodontus-portusjacksoni/](https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/heterodontus-portusjacksoni/) * *Anarhichas denticulatus*: Havforskningsinstituttet\ [https://www.hi.no/resources/klimastatus-pa-bestander/20211214_Northern-wolffish_narrative.pdf](https://www.hi.no/resources/klimastatus-pa-bestander/20211214_Northern-wolffish_narrative.pdf) * *Hydromantes italicus*: AmphibiaWeb\ [https://amphibiaweb.org/species/4076](https://amphibiaweb.org/species/4076) * *Rana clamitans*: Texas Parks and Wildlife Department\ [https://tpwd.texas.gov/huntwild/wild/species/bronzefrog/](https://tpwd.texas.gov/huntwild/wild/species/bronzefrog/) * *Coregonus clupeaformis*: StoreFish Database\ [https://storefish.org/species/coregonus-clupeaformis](https://storefish.org/species/coregonus-clupeaformis) **Adult mass references (AdultMass.REF)** Adult body mass values for **fishes, amphibians, and reptiles** were converted from size measurements (e.g., total length, snout–vent length) using the following online sources. (Only a selection shown; full list in data file.) * *Thamnophis sirtalis* – [https://animaldiversity.org/accounts/Thamnophis_sirtalis/](https://animaldiversity.org/accounts/Thamnophis_sirtalis/) * *Lachesis stenophrys* – [https://animalia.bio/lachesis-stenophrys](https://animalia.bio/lachesis-stenophrys) * *Python molurus* – [https://en.wikipedia.org/wiki/Indian_python](https://en.wikipedia.org/wiki/Indian_python) * *Porthidium nasutum* – [https://en.wikipedia.org/wiki/Porthidium_nasutum](https://en.wikipedia.org/wiki/Porthidium_nasutum) * *Natrix natrix* – [https://wildsideholidays.co.uk/grass-snake-natrix-natrix-culebra-de-collar/](https://wildsideholidays.co.uk/grass-snake-natrix-natrix-culebra-de-collar/) * *Zamenis longissimus* – [https://www.jungledragon.com/specie/15350/aesculapian_snake.html](https://www.jungledragon.com/specie/15350/aesculapian_snake.html) * *Vipera berus* – [https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/reptiles-and-amphibians/adder/](https://www.woodlandtrust.org.uk/trees-woods-and-wildlife/animals/reptiles-and-amphibians/adder/) * *Boa constrictor* – [https://en.wikipedia.org/wiki/Boa_constrictor](https://en.wikipedia.org/wiki/Boa_constrictor) * *Python regius* – [https://www.gbif.org/species/144100057](https://www.gbif.org/species/144100057)\ (Full list of 30+ taxa included in the dataset.) **Egg care references (EggCare.REF)** Sources used for documenting parental or egg care behavior: * AmphibiaWeb (e.g., *Plethodon jordani*, *Batrachoseps attenuatus*, etc.)\ [https://amphibiaweb.org](https://amphibiaweb.org/) * Animal Diversity Web (multiple taxa)\ [https://animaldiversity.org](https://animaldiversity.org/) * FishBase entries for lampreys and teleost fishes\ [https://fishbase.mnhn.fr](https://fishbase.mnhn.fr/) * Other sources: Animalia.bio, Wikipedia species pages, China Animal Scientific Database, HELCOM Red List Species, etc.\ (Full list as provided in data file.) **Fertilization references** * *Anarhichas denticulatus* – Species at Risk Public Registry (Canada)\ [https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/northern-wolffish.html](https://www.canada.ca/en/environment-climate-change/services/species-risk-public-registry/cosewic-assessments-status-reports/northern-wolffish.html) **Note** The online sources listed above represent supplementary materials or species-specific web resources that could not be fully cited in the formal reference list (e.g., museum databases, open taxonomic repositories, or field guides). All other references used in this study are properly cited as published literature (journal articles, books, or datasets) in the accompanying manuscript.