  Unusual elemental abundance patterns observed for stars belonging to nearby
dwarf spheroidal (dSph) galaxies are discussed. Analysis of the [alpha/H] vs.
[Fe/H] diagrams where alpha represents Mg or average of alpha-elements reveals
that Fe from Type Ia supernovae (SNe Ia) does not contribute to the stellar
abundances in the dSph galaxies where the member stars exhibit low alpha/Fe
ratios except for the most massive dSph galaxy, the Sagitarrius. The more
massive dwarf (irregular) galaxy, the Large Magellanic Cloud, also have an SNe
Ia signature in the stellar abundances. These findings suggest that the
condition of whether SNe Ia contribute to chemical evolution in dwarf galaxies
is likely to depend on the mass scale of galaxies. Unusual Mg abundances in
some dSph stars are also found to be the origin of the large scatter in the
[Mg/Fe] ratios and responsible for a seemingly decreasing [Mg/Fe] feature with
increasing [Fe/H]. In addition, the lack of massive stars in the dSph galaxies
does not satisfactorily account for the low-alpha signature. Considering the
assemblage of deficient elements (O, Mg, Si, Ca, Ti, and Zn), all of which are
synthesized in pre-SN massive stars and in SN explosions, the low-alpha
signature appears to reflect the heavy-element yields of massive stars with
smaller rotation compared to solar neighborhood stars.
