Associations between neoplasia incidence and telomere biology
We found that the prevalence of neoplasia is a good predictor of
malignancy prevalence (R2=0.90, β=0.7735±0.0489,
p<0.001, Fig. S2) across 29 mammal species included in Boddy
et al. (2020). Because neoplasia prevalence was available for more
species, analyses proceeded using this variable.
As expected, neoplasia rate was positively associated with TL (Fig. 3a)
and binary telomerase activity (Fig. 3d, marginally significant trend)
across the 22 mammal species shown in Table S9. Thus, a 1% increase in
TL predicts an absolute increase in neoplasia incidence of 0.21% (Fig.
3a). Neoplasia rate was negatively associated with lifespan (Fig 3b). A
1% increase in maximum lifespan predicts an absolute decrease in
neoplasia incidence of 0.14% (Fig. 3b). Species with some telomerase
activity (1) are predicted to show an absolute increase in neoplasia
incidence of 20.6% (Fig. 3d). There was no association between
neoplasia rate and mass (Fig. 3c). There was a marginal significant
positive association between TL and neoplasia rate, when accounting for
binary telomerase activity (Table 2).
Neoplasia rates could be biased towards higher estimates in domesticated
species due to the easier observation of large numbers of individuals
(Nagy et al., 2007; Ewald & Ewald, 2015; Boddy et al., 2020), which
could be associated with increased lifespan and senescence in captivity
(Tidière et al., 2016). We therefore tested, in a post hoc analysis,
whether the effect of TL on neoplasia rate was robust to controlling for
potential domestication effects on neoplasia rates (Table S6) or if the
effect of TL varied with domestication status (Table S7). TL remained
significantly positively associated with neoplasia rate when controlling
for domestication status and there was no effect of domestication status
on neoplasia rate (Table S6). The effect of TL on neoplasia rate did not
vary with domestication status (Table S7).