Phenotypic correlates of digit ratio in a wild bird: implications for the study of maternal effects

Garamszegi, László Zsolt; Hegyi, Gergely; Szöllősi, Eszter; Rosivall, Balázs; Török, János; Eens, Marcel; Møller, Anders Pape

doi:10.1016/j.anbehav.2006.11.023

Cited by 15 publications

(15 citation statements)

References 49 publications

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“…The hypothesis that digit ratio can function as an easily observed indicator of prenatal exposure to androgens stimulated a plethora of studies correlating digit ratio with developmental (e.g., Manning et al, 2003; Burley and Foster, 2004; Lutchmaya et al, 2004; Forstmeier, 2005), anatomical (e.g., McFadden and Shubel, 2002; Chang et al, 2006; Rubolini et al, 2006; Garamszegi et al, 2007), physiological (e.g., Manning et al, 1998, 2004; Manning and Taylor, 2001), and behavioral (e.g., Manning et al, 2000; Williams et al, 2000; Csathó et al, 2003; Bailey and Hurd, 2004; Bailey et al, 2004; Fink et al, 2004; Romano et al, 2005a; van Anders and Hampson, 2005; Millet and Dewitte, 2006; Saino et al, 2006a, b) measures implying that digit ratio may be a reliable predictor of evolutionary fitness (Manning, 2002).…”

Section: Sex Differences In Left and Right 2d:4d In House Sparrows Tmentioning

confidence: 99%

“…Close inspection of the data presented in Navarro et al (2007) indicates no sexual dimorphism in 2D:4D in house sparrows ( Passer domesticus ). Last, collared flycatchers ( Ficedula albicollis ) did not show significant sexual dimorphism in 2D:4D (Garamszegi et al, 2007). To date, there are no reports of unmanipulated male birds with lower 2D:4D than females.…”

Section: Sex Differences In Left and Right 2d:4d In House Sparrows Tmentioning

confidence: 99%

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Digit Ratio in Birds

Lombardo

Thorpe

Brown

et al. 2008

The Anatomical Record

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The Homeobox (Hox) genes direct the development of tetrapod digits. The expression of Hox genes may be influenced by endogenous sex steroids during development. Manning (Digit ratio. New Brunswick, NJ: Rutgers University Press, 2002) predicted that the ratio between the lengths of digits 2 (2D) and 4 (4D) should be sexually dimorphic because prenatal exposure to estrogens and androgens positively influence the lengths of 2D and 4D, respectively. We measured digits and other morphological traits of birds from three orders (Passeriformes, house sparrow, Passer domesticus; tree swallow, Tachycineta bicolor; Pscittaciformes, budgerigar, Melopsittacus undulates; Galliformes, chicken, Gallus domesticus) to test this prediction. None were sexually dimorphic for 2D:4D and there were no associations between 2D:4D and other sexually dimorphic traits. When we pooled data from all four species after we averaged right and left side digits from each individual and z-transformed the resulting digit ratios, we found that males had significantly larger 2D:4D than did females. Tetrapods appear to be sexually dimorphic for 2D:4D with 2D:4D larger in males as in some birds and reptiles and 2D:4D smaller in males as in some mammals. The differences between the reptile and mammal lineages in the directionality of 2D:4D may be related to the differences between them in chromosomal sex determination. We suggest that (a) natural selection for a perching foot in the first birds may have overridden the effects of hormones on the development of digit ratio in this group of vertebrates and (b) caution be used in making inferences about prenatal exposure to hormones and digit ratio in birds.

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Section: Sex Differences In Left and Right 2d:4d In House Sparrows Tmentioning

confidence: 99%

Section: Sex Differences In Left and Right 2d:4d In House Sparrows Tmentioning

confidence: 99%

Digit Ratio in Birds

Lombardo

Thorpe

Brown

et al. 2008

The Anatomical Record

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“…Our understanding of the evolutionary and developmental processes that underpin digit ratios grows with each new species. Species studied to date include primates (Roney et al, ; McIntyre et al, ; Nelson and Shultz, ), laboratory mice ( Mus musculus ) (Brown et al, ), field voles ( Microtus agrestis ) (Lilley et al, ), wood mice ( Apodemus sylvaticus ) (Leoni et al, ), David's rock squirrels ( Sciurotamias davidianus ) (Lilley et al, ; Zhao et al, ), red squirrels ( Tamiasciurus hudsonicus ) (Gooderham and Schulte‐Hostedde, ), house sparrows ( Passer domesticus ) (Navarro et al, ), ring‐necked pheasants ( Phasianus colchicus ) (Romano et al, ), tree swallows ( Tachycineta bicolor ), budgerigars ( Melopsittacus undulates ), chickens ( Gallus domesticus ) (Lombardo et al, ), zebra finches ( Taeniopygia guttata ) (Burley and Foster, ; Forstmeier, 2005, ), dark‐eyed juncos ( Junco hyemalis ) (Cain et al, ), collared flycatchers ( Ficedula albicollis ) (Garamszegi et al, ), pied flycatchers ( Ficedula hypoleuca ) (Ruuskanen et al, ), barn swallows ( Hirundo rustica ) (Dreiss et al, ), common wall lizards ( Podarcis muralis ) (Rubolini et al, ), humble anoles ( Anolis humilis ) (Direnzo and Stynoski, ), green anoles ( Anolis carolinensis ) (Chang et al, ; Lombardo and Thorpe, ), border anoles ( Anolis limifrons ), tree skinks ( Mabuya planifrons ) ( Rubolini et al, ), painted dragon lizards ( Ctenophorus pictus ) (Tobler et al, ), species from the family Iguanidae (Gomes and Kohlsdorf, ), Bransford's robber frogs ( Craugastor bransfordii ) (Direnzo and Stynoski, ), strawberry poison dart frogs ( Oophaga pumilio ) (Chang, ), great creasted newts ( Triturus cristatus ), alpine newts ( Mesotriton alpestris ), Carpathian newts ( Lissotriton montandoni ), and smooth newts ( Lissotriton vulgaris ) (Kaczmarski et al, ). As might be expected with such a diverse array of taxa, sexually dimorphic patterns in digit ratios have been shown to vary across species (Fig.…”

mentioning

confidence: 99%

No Sexual Dimorphism Detected in Digit Ratios of the Fire Salamander (Salamandra salamandra)

Balogová

Nelson

Uhrin

et al. 2015

The Anatomical Record

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It has been proposed that digit ratio may be used as a biomarker of early developmental effects. Specifically, the second-to-fourth digit ratio (2D:4D) has been linked to the effects of sex hormones and their receptor genes, but other digit ratios have also been investigated. Across taxa, patterns of sexual dimorphism in digit ratios are ambiguous and a scarcity of studies in basal tetrapods makes it difficult to understand how ratios have evolved. Here, we focus on examining sex differences in digit ratios (2D:3D, 2D:4D, and 3D:4D) in a common amphibian, the fire salamander (Salamandra salamandra). We used graphic software to measure soft tissue digit length and digit bone length from X-rays. We found a nonsignificant tendency in males to have a lower 2D:3D than females; however, no sexual differences were detected in the other ratios. We discuss our results in the context of other studies of digit ratios, and how sex determination systems, as well as other factors, might impact patterns of sexual dimorphism, particularly in reptiles and in amphibians. Our findings suggest that caution is needed when using digit ratios as a potential indicator of prenatal hormonal effects in amphibians and highlight the need for more comparative studies to elucidate the evolutionary and genetic mechanisms implicated in sexually dimorphic patterns across taxonomic groups.

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“…For example, in the case of the linear relationship between variables, the ratio ( y/x) is not dependent on size only when the intercept b of the equation y ¼ ax þ b is zero. In a wild bird species, Garamszegi et al (2007) have shown that 2D and 4D scale allometrically with other body parts and with each other. If the allometric slopes are different for different digits the 2D : 4D ratio may be affected.…”

Section: Introductionmentioning

confidence: 99%

Differences in the 2nd to 4th digit length ratio in humans reflect shifts along the common allometric line

Kratochvíl

Flegr

2009

Biol. Lett.

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Ratios often lead to biased conclusions concerning the actual relationships between examined traits and comparisons of the relative size of traits among groups. Therefore, the use of ratios has been abandoned in most comparative studies. However, ratios such as body mass index and waist-to-hip ratio are widely used in evolutionary biology and medicine. One such, the ratio of the 2nd to the 4th finger (2D : 4D), has been the subject of much recent interest in both humans and animals. Most studies agree that 2D : 4D is sexually dimorphic. In men, the 2nd digit tends to be shorter than the 4th, while in women the 2nd digit tends to be of the same size or slightly longer than the 4th. Nevertheless, here we demonstrate that the sexes do not greatly differ in the scaling between the 2nd and 4th digit. Sexual differences in 2D : 4D are mainly caused by the shift along the common allometric line with non-zero intercept, which means 2D : 4D necessarily decreases with increasing finger length, and the fact that men have longer fingers than women. We conclude that previously published results on the 2D : 4D ratio are biased by its covariation with finger length. We strongly recommend regression-based approaches for comparisons of hand shape among different groups.

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Phenotypic correlates of digit ratio in a wild bird: implications for the study of maternal effects

Cited by 15 publications

References 49 publications

Digit Ratio in Birds

Digit Ratio in Birds

No Sexual Dimorphism Detected in Digit Ratios of the Fire Salamander (Salamandra salamandra)

Differences in the 2nd to 4th digit length ratio in humans reflect shifts along the common allometric line

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